The dragonfly hung in the thick, humid air like a jeweled miracle, wings beating so fast that they became a blur. Its body was an oil slick of shifting colors, greens and blues and purples, blending together in patterns that would have seemed garish if they hadn’t been natural.

It had a cocker spaniel clutched in four of its six legs. I scowled to see it. Dogs are rare these days; dogs that don’t have defensive, paranoid owners ready to die to protect them are even rarer. My family could have eaten for days off that carcass, and instead, it was going to the dragonflies, who wouldn’t even appreciate what they had. Insects never did. Their lives were all about the mechanics of survival, and not about the little joys that could come with it: They ate, they fucked, they slept, but they didn’t enjoy. Even reptiles enjoyed. Insects . . .

Insects existed. That was what Nature had made them to do, and that was what they were going to keep on doing, right up until somebody found a way to stop them.

Someone tugged on my sleeve. I turned. My baby sister was crouched down beside me, her respirator clamped firmly over her mouth, her spear clasped with equal firmness in her hands. She looked terrified, and rightly so. She was just thirteen years old, underfed and underdeveloped, but old enough to go out into the city with me to scrounge for food. She’d never seen a dragonfly in proper flight before.

“Why are we standing here?” she whispered.

“Because dragonflies eat mosquitoes,” I said. “If there’s a dragon here, there’s not going to be a sucker, and dragons can’t be quiet. You’ll always hear them coming.” The dog must have been old, or deaf, or otherwise infirm; any healthy animal would have found a way to get away.

Molly blanched. “Mosquitoes?” she whispered, in a terrified tone.

“Not here,” I reassured her. “They don’t go where the dragons are. Now come on. Let’s move.”

The dragonflies droned overhead, dangerous and beautiful, as we slipped back into the alley and disappeared.

• • • •

There are no small changes. There are only changes with consequences no one quite foresaw.

Deforestation became a problem after the climate changed: Countries burned and forests died, and there were so many dead spots in the ocean that people began talking direly about how the sky was going to change and leave us all gasping for breath. Then it actually started to happen. The air got thin. I was only ten at the time, a little younger than Molly is now, but I remember my parents stockpiling oxygen tanks and warning me to keep the windows closed, to keep our artificially enriched atmosphere from getting out. The reduced oxygen levels helped a little with the fires. That was the only good thing they did. The plants did okay—they make oxygen, they don’t use it—but everything else was dying.

So a bunch of clever scientists did what clever scientists have always done, and started looking for an answer. Someone hit on the idea of super-oxygenating algae, capable of growing in the oceanic dead zones, capable of pumping out eight, nine, even ten times the oxygen of normal algae. Humanity was desperate. Humanity was dying. The algae got pushed through approvals at the speed of terror, and dumped into oceans all over the world, where it began to do its job. It spread like a green cloak across the water, oxygenating air and sea alike. Sure, some fish probably died, but the fish had been dying anyway, suffocating under the weight of the water. A few had to be sacrificed to save the many.

The air started getting better. That was when my parents had decided to have a second child, to celebrate the salvation of the world. Molly had been born in the lee of the storm, that brief, beautiful moment when the air was breathable and the world was ours again.

But the algae didn’t have an off switch. No one had stopped to consider the fact that oxygen is a poison: that mammals evolved to breathe something that was killing us, one lungful at a time, or that once, the world had been a much more densely oxygenated place. Once, silly things like the square-cube law hadn’t really held much sway, because the air had been so heavy that the insects could stand up proud and tall and dominate their environment. And the algae didn’t have an off switch.

Molly had been two years old when the respirators became necessary again, this time to filter out the oxygen, which had reached levels that were uncomfortable for human lungs. She had been four years old when mosquitoes the size of kittens had started to appear in Florida and Costa Rica. And she had been six years old when a praying mantis had come in through a broken window and eaten both our parents in their beds.

It’s a whole new world.

We did this to ourselves.

• • • •

Dragonflies were predators, capable of reaching eight feet in length toward the end of their lives. The young, healthy adults were usually only four to six feet long. Still dangerous, but not big enough to take on a full-grown human. They weren’t smart, but they still knew better than to mess with things that could hurt them if they had any other choice.

Nymphs weren’t quite as good at self-preservation as the adults. They were all appetite and aggression, and they would snap at anything that entered the water. They did an amazing job of keeping the mosquito larvae under control—good thing, too; without them, humans would have gone extinct as soon as the mosquitoes reached the size of eagles—but they also ate the fish, and the frogs, and everything else big enough to be a mouthful. Fishing these days was all about the dragonfly nymphs.

Molly had an amazing knack for spearing the quick, slippery things as they darted by under the surface of the water, chasing the shadows we cast on the pond. She stabbed, and when she pulled back her spear, there was a nymph the size of a housecat impaled on her hook. It was thrashing madly, all six of its legs seeking and failing to find purchase against the shaft of the spear. It wanted to survive. I couldn’t blame it for that. All any of us has ever been trying to do is survive. Humans destroyed the old world trying to live in it, and now that we have a new world, we’re still fighting to stay alive, no matter what that might entail.

I opened the cooler and put it down between us, using my foot to help lever the squirming nymph off the spear and into the white plastic box. I slammed the lid back into place before the nymph could buck its way out, and gave Molly the thumbs-up to go back to fishing. We weren’t the only hunting party out for the afternoon, but none of the others had Molly’s skill with the spear; it was up to us to feed the family, if anybody could.

Mark and his urchins would be scavenging in the old Financial District, combing through towers of glass and steel that were more unstable and more picked-over with every year that passed, looking for those precious cans of pre-change food. Most of them had expired years ago, but as long as they weren’t bloated or punctured, they were still worth the risk. Everyone I knew would rather die on a full belly than an empty one—another thing we shared with the insects. Hunger was universal, shared across the animal kingdom, hated by hot- and cold-blooded creatures alike. Hunger was the antithesis of survival.

Maybe that was why we’d been able to do so much damage before everything fell apart. Humans were always hungry. Even on a full stomach, with all our needs met and all our wanting answered, we were hungry.

Molly squealed as she slammed her spear into the body of a second nymph. It was a small, giddy sound: the sound of eating well, the sound of knowing that she had contributed to the group, not merely continued to exist as something that took up resources and occupied space. She’d only been going hunting with me for three years, and there was still so much about the bright world above that was new and delightful to her. We’d been with this colony since a year after our parents died, and she’d spent the three years between home and hunter as my protected shadow. I’d never allowed her to go with Mark and his urchins, or to accompany the other smaller ones on their spider-spotting runs. After Mom and Dad, she was the only thing I had left, and so I’d been prepared to do anything to protect her. Even work double-hard to keep her from needing to work at all.

Molly was always scared, but she had never liked to be coddled. Once she’d turned ten, there had been no chance of my keeping her hidden from the world any longer. Terrified, she’d picked up her spear and followed me into the light, respirator over her face to keep her breathing, surgical gloves over her hands to keep her sweat from scenting the air and telling the other predators what and where she was. Even now, two years later, she was always scared, and she was always willing to accompany me out into the light.

Bravery isn’t the absence of fear. It’s the willingness to keep going despite it. My baby sister was the bravest person I knew.

“How many do we need?” she asked.

“Five should be enough.” Five would buy us a share of anything that came back with the other groups, no matter how rare or precious: Five would be meat for stews, for frying, maybe even for making jerky, which would mean meat later in addition to meat now. Meat later was almost a fantasy, too decadent to be real.

Molly nodded. I helped her scrape the second nymph into the cooler, where the first had stopped thrashing, and she turned her attention back to the water. The air was still. No drone of dragonflies, no buzz of mosquitoes. I allowed my shoulders to unlock, enjoying the brief moment of peace. We never thought about how many insects we existed alongside when I was a kid; we never considered that mammals were in the minority, that only size and the slow change in the oxygenation in the air had made this world ours, instead of being theirs, as it should have been from the beginning.

We were foolish. We paid the price. Molly, though . . . Molly never had the chance to be a fool. She’d been too young to buy into the system of broken values and limitless consumption that had pushed us, one seemingly inevitable step at a time, into a world where dragonflies ruled the sky and spiders ruled the ground.

Spiders. I stood suddenly upright, considering the noise—or lack thereof—in a new light. There were dragonfly larvae here, because there was water, but there were no adult dragonflies. No damselflies, no lurking grasshoppers or wood lice. Why not? There was water here, and thriving vegetation. This should have been an insect’s paradise. Where were they?

“Molly, I think this should be the last one,” I said, voice tight, shoulders locked.

“I can get two more,” she protested, and stabbed at the water again.

I didn’t want to tell her my suspicions. Sending her into a panic wouldn’t change anything, but it could make it a lot harder for us to get back to safety: Even at thirteen, she could slow me down immensely if she lost her ability to cope with the world. Leaving her behind wasn’t an option. It hadn’t been on the night our parents died, and it wasn’t going to become an option now just because I was scared and she was old enough, supposedly, to run under her own power. Maybe she was the last sheltered child in the world. If that was so, then I was going to pay to keep her that way.

“We don’t need two more,” I said. “Three is enough. We can pay for our share of dinner, maybe even get something sweet for later on. Being greedy isn’t going to get us anything.”

Her head snapped up, eyes narrowing as she tried to decide what had gotten into me. Little sisters will always be the same, no matter how many times the world ends and begins anew, changed but still enduring. Molly always knew when I wasn’t telling her something. “What’s wrong?” she demanded.

“Please,” I said. “We need to go.”

“All right—” she said, pulling her spear out of the water and taking a step back toward me. Her feet squelched against the mud, a thick, sucking sound that seemed to echo forever.

She never even saw the spider that came out of the brush and grabbed her. It was a vast, brown, bristling thing, a beast made entirely of broom handles and briars, like a monster scarecrow from another world. Its jaws clamped on the back of her neck, and her eyes widened in surprise before she went limp.

I screamed, not caring what the sound might attract, and charged for the spider. Sometimes, if they were surprised enough, they would drop their prey and retreat, choosing the luxury of living to eat another day over the bounty of whatever they were trying to take. This one was braver than the norm, or just more comfortable in its surroundings, because it didn’t let go of her as it scurried backward, into the brush, dragging Molly along.

The brambles seemed to open up as the spider moved, allowing it to pass with my sister, only to seal themselves again behind it. The spider was gone, and so was Molly, and the scene had played out in a matter of seconds.

I dropped to my knees in the mud, listening to the last of the dragonfly nymphs thrashing in the cooler, and screamed.

• • • •

One of the other foraging teams found me there, curled up around our cooler, my spear clutched loosely in my right hand, and Molly gone. It was a miracle, they said, once they had me back in the tunnels, back in the illusion of safety: They didn’t know how long I’d been lying there, but anything longer than a few seconds should have been enough to spell my doom. Where there was one spider, there were likely to be more, especially in a feeding ground as fertile as the edge of a pond where the dragonflies came to spawn.

I didn’t learn about any of this for days. I was in shock, locked inside my own mind, watching as the scene played out over and over again. Sometimes, in my dreams, I was able to move just a fraction of an instant before the spider appeared, grabbing Molly and yanking her to safety, so that its mandibles closed on empty air. Other times, it would bite down harder, severing her head in a single blow, and then it would come after me, sparing me the anguish of living in a world where I had failed.

But nothing, not even shock, can last forever in a world where the air kills and the things you used to squash in the shower can come for you in the night. Three days after Molly and I had gone out hunting, I opened my eyes and found myself looking at the tunnel roof, gray concrete and industrial lighting powered by the turbines connected to our underground river. The hiss of the air conditioning was a comforting constant, reassuring me that the oxygen levels here were safe for me to breathe, and more, were unsafe for the things that hunted the world outside. The square-cube law operated here exactly as it always had. Any bugs that decided to follow a hunting party inside would collapse under their own weight as their lungs failed to pull sufficient oxygen from the air. The old air was safety.

Safety. “Molly,” I gasped, sitting upright. I was wearing hospital scrubs, old and blue and oft-bleached, used as pajamas and recovery clothes by hundreds since the collapse.

“You’re awake.”

I turned. The voice belonged to Mark, for once apart from his squad of scavenging urchins. He was holding my spear. My eyes widened, and I leaned over to snatch it from his hands before I could think better of the gesture.

Mark smiled. Not happily, but a smile all the same. “I was wondering whether you’d still want that. Miss Nancy doesn’t think you will. She says this is going to drive you underground for good.”

“Molly,” I said again, and stood—or tried to. My legs wobbled, refusing to hold me up. I collapsed back onto the cot.

“Slow down, superstar, you’re just going to hurt yourself,” said Mark, leaning over to put a carefully restraining hand on my arm. “It’s been three days. We’ve had search parties combing the area where we found you. There’s been no sign of your sister.” Unspoken: If there hadn’t been a sign within three days, there probably wasn’t going to be one. Anything that was hungry enough to hunt humans wasn’t going to leave them unconsumed.

And if I allowed myself to start thinking that way, I was failing her all over again. How many times was it possible for me to fail my sister? God help me, but I was starting to feel like I might find out.

“I need food, water, weapons,” I said. “I have to find her.”

“I agree.”

“You don’t under—” I stopped. “You do?”

“Three of my kids have disappeared in the last two weeks. Spiders. Big spiders, just like the one you were raving about when we found you. But we haven’t found bodies, and we haven’t found bones, and people are too damn willing to write them off as lost. I think some people are even glad.” His voice turned bitter at the end, stressing the word “glad” like it was the worst thing anyone had ever said, or thought, since the air had turned against us. “Kids like mine don’t bring in as much as they consume. They never could. Nobody wants to be the one who says we should turn them out—that would be taking a step over the line into monster, and I guess we still think of ourselves as too human for that—but everybody thinks it. Everybody looks at what’s on their plate and thinks ‘this would be more without them,’ and then they look at my kids, and they wish something like this would happen.”

“Not everybody,” I said softly.

His laughter was even more bitter than his voice. “No, everybody,” he said. “At least once. Even me, when I was hungry and tired and every one of those kids looked like my son, and not one of them was him. Even you. I’ve seen it, when you were hungry and cold and Molly was sleeping sound, and not understanding how much you’d given up to keep her safe. We’re both parents to other people’s children. We’re never going to be parents to our own. Not again, for me. Not ever, for you.”

“You don’t have to talk to me like that when my sister is missing,” I said, my voice dropping until it was barely above a whisper.

Mark shook his head. “Yes, I do. You need to understand that no one’s going to help us look for her. I’ll help you. I want to help you. But if you start asking for permission, they’re going to tell you no. They’re going to say that you already owe the community for your care, and demand that you pay them back before you go looking for her. And then the trail will go colder than it already has, and by the time you find your way back into the world, there won’t be anything to find. Do you understand? We go now. We go quietly. We go together. Or neither one of us is going to go at all.”

I was quiet for a moment, just looking at Mark, trying to collect my thoughts. He looked calmly back. He was a few years older than I was, and had arrived at the community at roughly the same time. When he’d come in, it had been with an armful of solemn, wide-eyed little boy, no more than two years old. David, his son. David, who had been born to this strange, terrible new world, who hadn’t lived in it for long enough to learn how to be careful.

David, whose life had ended in the buzz of dragonfly wings, and the screams of his father trying against all odds to chase the monster into the sky. But Mark had survived the loss. Mark had recovered from it, even if he’d never been the same man again, and he’d found other ways to contribute to the community. He’d learned to care for the children whose parents couldn’t, or whose parents had died getting them to us. He’d learned to be a father to dozens, when he could no longer be a father to one.

We weren’t friends. All my energy and attention had been reserved for Molly—and maybe I’d even felt a little superior to him, because my sister had still been there, and his son hadn’t. His son had been long, long gone.

“Do you know where to go?” I asked.

“I know where to start,” he said.

• • • •

We crept through the shadows of the early morning, respirators on our faces and packs weighing down our shoulders. The door to the community’s subterranean warren was behind us, closed and essentially forgotten, because unless we found the children, we could never go back. We’d stolen. We’d taken unauthorized supplies and unapproved equipment, carrying it with us up to the surface, to help us look for the children that no one actually wanted us to find.

But Mark was right when he said that no one could admit that. If we found them, if we brought them safely home, we would be allowed back inside. We’d be punished, penalized for what we’d taken, but no one would ask for us to be exiled, because exiling us when we’d just gone to retrieve our children would be the act of monsters. If we found them, everything could go back to the way it had always been. And if we didn’t find them . . .

If we didn’t find them, it wouldn’t matter that we’d be exiles. It wouldn’t matter that we’d die alone and afraid, torn apart by the menace we had created. Because if we didn’t find them, I would have failed Molly the way I’d failed our parents, and I would deserve everything the world wanted to do to me. If I couldn’t save her, I didn’t deserve to have a home.

More oxygen in the air meant more CO₂, which meant more food for the plants; they thrived in this transformed atmosphere. Mark and I pushed our way through a field of chest-high crabgrass, always watching our feet. Stepping on a resting wood louse was surprising and unpleasant, but not necessarily fatal. Stepping on a sleeping centipede could cost a foot at best, and a leg at worst. Either one would mean a quick and brutal death. The smell of blood attracted more things than I liked to think about, and most of them were happy to feast on man-flesh. Call it revenge for all those rolled up newspapers and plastic cups of my youth, back when the world had been ours, instead of theirs.

“We try to scavenge as far from water as we can, to prevent accidents,” said Mark. “It’s not safe anywhere, but the water . . .”

“The water attracts,” I agreed quietly. Not just insects, although they had grown first, swelling beyond the bounds of the old nature, adapting to the new one: other arthropods were making their own adaptations. There used to be a fisherman with the community, a man who’d fled inland from the sea, shattered and still shaking from the gale-force winds that had erased his hometown from the face of the world. He’d gone to the streams outside the city, using reel and rod to tease crawfish out from beneath rocks and bring them back to feed us. When he’d started, they had been small things, six inches at most. Over the span of three years, they had swelled to a foot, and then two feet, and finally more than three feet, great monsters of the shallows, all claws and chitin.

And then he had gone out and not come back. We all knew that his bones—what was left of them—were somewhere at the bottom of the stream, disarticulated by the crawfish, stripped bare of flesh and forgotten. We didn’t know how big the crawfish were now. The water was hyper-oxygenated, like everything else. They could be monsters in the deep, and we had given that to them.

There were still frogs. Sometimes I heard them croaking when I went out at twilight, and they sounded big enough to swallow the sky. Everything was growing. Everything but us. Maybe, given time, the dinosaurs would rise again, taking a second shot at the world that should have been theirs all along. I wondered, sometimes, whether they would be grateful to us for fixing it for them, or whether they would just keep moving forward, marking time until things changed again.

“Shhh,” said Mark, putting out a hand like I was one of his urchins, too young to know when I needed to be careful. It burned. I stopped all the same, freezing in place, trying to listen for what he’d heard that I hadn’t. Pride has no place in the open air.

Something rustled in the grass ahead of us. We held our place and our peace as a ladybug as large as a dinner plate crawled out, antennae waving, mandibles working against the air. I stiffened. Ladybugs were staples of picture books and cartoons when I was a child. I hadn’t realized until later that they were vicious predators, capable of killing and consuming insects twice their size. We were too big for this ladybug to devour, but that didn’t mean it wouldn’t try if it felt threatened.

The only good thing about its presence was that it meant there were probably no mantises in the area. The stealthy ambush hunters snatched up ladybugs like children snatched up candy, devouring them whole. They could coexist, but they usually didn’t.

The ladybug bumbled on. We started moving again, pushing deeper into the grass, moving toward Mark’s unidentified goal. I forced my breathing to stay level. Some insects tracked by following trails of carbon dioxide, using our lungs against us. The respirator meant that I was putting off less than I would have been without it, but less wasn’t the same as nothing at all. It could still be followed. Breathing too fast would just set me up to be devoured.

Then Mark stopped. “Here,” he said, indicating an open doorway, a black cavern into a deserted store. The logo was still visible, red circles against grimy stucco. This had been a wonderland once, taken for granted by the people who walked through its automatic doors into its climate-controlled depths, where the shelves groaned under the weight of so many good things. Vitamins and bottled juices and chocolate; clean clothes and solar batteries that were new, not worn out and run down by years of constant use. Sometimes I thought that if I had a time machine and an hour, and knew that I couldn’t change the world enough to make a difference, that I would spend it looting a store just like this one, stealing from the past the way the past had stolen from all of us.

None of that changed the fact that walking through those shattered doors would be just this side of suicide. “You can’t be serious,” I hissed. “That’s . . . that’s enclosed space.” Enclosed space that hadn’t been reclaimed and cleaned out by human hands; enclosed space that could harbor anything at all. Insects like the dark.

“I know,” said Mark. He looked at the doors. “We were near here when I lost the first of them. I didn’t want to think he could be in there, but now I think there’s not anywhere else any of them could be. We have to go in.”

“And if it kills us?”

“Then it kills us, and we don’t have to do this anymore.” There was a quiet resignation in his voice that I had heard before, in my own, in everyone else within the community’s. We were struggling to hold on because we didn’t see another way; because to be human was to struggle, to keep trying in the face of impossible odds. But here was a choice that meant continuing to struggle while also admitting that maybe, just maybe, we were done.

I closed my eyes. Molly’s face looked at me from the darkness, all pale cheeks and desperation. I opened them again, turned to Mark, and nodded.

“All right,” I said. “We’re going in.”

• • • •

Scavenging teams had been here, pushing as far in as they dared before abandoning the effort as more risk than reward. The shelves near the front of the store were picked clean of whatever they’d once held, be it food, medication, or the latest DVDs. It didn’t matter that most people didn’t have a way of playing DVDs anymore, or that seeing the pre-change world caused depression and mania in a lot of our older survivors; if something had been touched by human hands, created by human hands, people wanted it. People wanted to remember that once, we’d been the dominant species on this planet, not reduced to living in ruins and waiting for the sky to fall. People wanted to pretend that one day we were going to be the dominant species again.

People were fools. The world belonged to the crawling things now, to the bugs and spiders and frogs. And maybe part of the world belonged to the children like Molly, who were young enough not to mourn for something that was never coming back. The old world was dead and gone and buried. Molly and her kind, they could build a new one from the wreckage. People like me and Mark? We were here to get Molly’s generation to adulthood, to protect them in the remains of the world our parents had destroyed until their time could truly begin. We were the liminal generation.

It was an awful thing to be. We were trapped in the doorway between worlds, enough part of what was lost that we would never stop regretting it, enough part of what was found that we looked askance at the people behind us, the ones who were never going to move on. We couldn’t adapt, not really. All we could do was struggle to keep the ones who could alive.

Mark took the lead as we crept deeper into the old super store. He’d clearly been here before; he knew where to put his feet, where the floor would hold him, while I had to trust that he wasn’t guiding me to my death. Only the fact that you can’t bargain with insects kept me from turning and running back to the light. He wasn’t going to trade me for his missing kids. Whatever had taken them would just take him too. One more piece of meat to fill its belly. One more death for the ever-mounting toll.

Would the world even notice when humanity was gone? Had it noticed when the last dodo died, or when the last of the dinosaurs lay down and closed its eyes for good? We’d been so foolish, thinking anything we did could destroy the world. The world didn’t care about us. All we’d ever been in a position to destroy was ourselves.

“Hold on,” whispered Mark. He stopped, and so did I, watching silently as the dark outline of his body bent, fiddling with something near his feet. Then a light came on, red as blood or rust, illuminating the room in front of us. I clapped a hand over my respirator, like I could somehow muffle the urge to scream, or stop the small traces of carbon dioxide from coming through the vents.

The air glistened with webbing, glowing crimson in Mark’s light, like some sort of terrible Christmas. Spiders scurried along the loops, treating them like makeshift highways. Most were the size of dogs, cocker spaniels and pit bull terriers. They paid us no mind. We were too big for them to eat and we weren’t moving fast enough to be a threat; as long as we left them alone, they were going to return the favor.

Mark took a step forward. The light moved with him. I realized that it was attached to his shoe, tilted upward, so that he’d always be able to see where he was going. It was the sort of good idea I’d never needed to have, thankfully; Molly and I had always done our hunting in the light.

Mark was still moving. I followed. There was nothing else for me to do. Not when there was a chance that Molly was still alive somewhere in here.

The webs got thicker as we moved into the store. There was no natural light here; these places had always been built to minimize the presence of windows and make it easier to control the internal temperature. Both things that made them perfect nests for the things that owned them now, the dark and crawling creatures that had come up from the soil and taken the world for their own. A strand of webbing brushed my cheek. I shuddered and clawed it away, resisting the urge to turn and run. The webs were only going to get thicker from here.

What had Molly thought as she was dragged into the dark? Had she believed that I would let her die, or had she known that I would come for her? I thought of her face, innocent and sweet and all I had left of my family, and I kept moving, until we reached a solid wall of web. It stretched from the floor to the ceiling, so thick that it looked like something out of a nightmare. This wasn’t possible. This shouldn’t have been possible.

“Through here,” whispered Mark. He produced a knife from his belt and began to cut, untangling the strands of web with a speed and skill that spoke of long practice. I looked nervously from side to side, waiting for some great monster to rush at us and bring this ill-fated adventure to an end. Nothing moved but the small spiders—small is always a relative term—and they were still ignoring us.

“How do you know?” I whispered back.

“Because wolf spiders hunt during the day, and they like to make larders,” said Mark. His logic was chillingly simple. “Twilight is when this place gets hopping. Now come on.” He pried the hole in the webbing wider, until we could fit through, single-file. I slipped past him, and stopped.

Light had come back into the world.

At some point in the last decade, the roof of the store had caved in, giving way in the face of wind and weather. The spiders had done their best to close off this avenue for the sun, stringing their webs across the hole until the light was washed-out and gray, filtered through a hundred layers of silk. It didn’t matter. I could see now, and what I saw was terrible.

Dozens of cocoons dangled on silken threads, some as small as a wood louse or a squirrel, others larger than a human being. I didn’t want to think about what might be in those larger cocoons, or how big the spider that dragged it back here would have needed to be. Spiders could handle prey that was larger than they were, but normally only if they were webbing it on the spot; not if they were carrying it back to save for later.

How big were they getting, around the edges of the world where humanity was already a fading, forgotten dream? How big were they going to get, now that we’d removed the limits? I hadn’t been old enough when things had changed to know much about pre-oxygen insect life, and the older people never wanted to talk about it at all. They just turned their faces to the wall and refused to admit what they’d done.

Mark began moving forward, eyes on the cocoons. I followed. The older ones tended to be darker in color, the webbing attracting and holding small particles in the air. I was looking for something small, something fresh, something long enough to hold a sister and bright enough to be new.

In the dimness beside me, I heard Mark gasp, a single short, sharp intake of breath that was followed by the softer sound of weeping. He’d found one of his missing ones, and they hadn’t been in the condition he’d been hoping. But his children had been missing longer than mine had. Molly still had a chance.

Something buzzed, close enough to my head that I jumped and nearly toppled over, seized with cold dread. I looked up. It was the dragonfly we’d seen earlier, the dog still clutched in its front legs. It wasn’t cocooned. Webbing was wrapped around its wings, pinning it in place, but it wasn’t cocooned. The buzz had been it struggling to be free, as startled by the sight of me as I was by the sound of it.

Beyond the dragonfly was a row of fresh cocoons. I took a steadying breath and moved in that direction, knife at the ready.

I found Molly in the third cocoon I cut down. Her eyes were closed and her face was serene. She looked like she was sleeping. She was beautiful—she had always been beautiful—but until that moment, I hadn’t fully appreciated that beauty for what it was. She was one of the first daughters of this brave new world, with calluses around her mouth and nose from her respirator, and skin as soft as flower petals. I stroked her cheek. She wasn’t breathing.

Well, of course she wasn’t breathing. She didn’t have her respirator. Carefully, I unhooked my own and placed it on her face, tightening the straps until it fit just so. Her eyes never opened. But they would. They would. They had to. I had promised our parents that I would keep her safe, and she was going to open her eyes. She was going to remember how to breathe. She was going to endure. She was going to thrive. She had to. And if she didn’t, then I wasn’t going to either. All or nothing. That was the way.

Mark made a small choking sound. I turned, and there was no terror as I saw that he’d been grabbed from behind by a behemoth of a spider, something so large and horrible that my mind refused to accept it. It was impossible. It was the inevitable result of the world’s changes, and it was too much. My sister was gone, my lungs were growing heavy and thick with too much oxygen, and it was too much.

Mark didn’t even have time to scream.

The dragonfly buzzed again, alarmed by the nearness of the spider. There were no alliances to be formed here, no unions against a common enemy: The minds of mammals and the minds of insects were too different. But there was something to be said for revenge. I ran to the dragonfly’s side, grabbed the webbing that held it, and began to slice. It bucked and writhed, flashing its mandibles in a threat display, making my task that much harder. I kept going, waiting for the moment when the spider would grab me and jerk me backward, into the dark. I cut, and cut, until suddenly, the dragonfly was free. Suddenly, it rose into the air, wings buzzing, and I realized that it was close enough to hurt me badly.

It didn’t. Instead, it turned, fleeing out the cracked hole in the ceiling, leaving me to my fate. I closed my eyes, resigned to the inevitable.

The sound of wings forced me to open them again, and I watched in helpless awe as the swarm of dragonflies poured in through the hole, following the one I had just cut free. They filled the air with darting, shining jewels, ranging in size from a few feet to larger than an adult man. The spiders reared onto their hind legs, threatening the attackers. The dragonflies descended, and battle was joined. Even the spider that had killed Mark left his body, racing to defend the nest. They wanted to live. They all wanted to live.

I had made a promise to my parents, and I was going to keep it; Molly needed my respirator if she was going to wake up (she wasn’t going to wake up), and so I snatched Mark’s from his face, fastening it to my own as I ran, out of the spider’s lair, through the memorial to mankind’s hubris, and out into the shimmering, newly primeval world.

I ran, and as long as I could keep running, I might be able to find another promise. I might be able to make a promise to myself. One that would be enough.