It still feels weird that we just left him out there,” Molly said.

Javi didn’t answer—he was busy stoking the fire. Everyone had changed into dry clothes when they got back to the airplane that morning, but they were still shivering from the cold night in the rain. Team Killbot all wore scavenged clothes now, the wrong sizes and colors and styles, like they were pretending to be other people.

People who were dead.

“The jungle can handle it,” Anna said. She rolled up the too-long sleeves of her shirt, a blank expression on her face.

Molly wasn’t in the mood for a biology lesson. The problem with the jungle was, it didn’t care about death. And Caleb’s death had to mean something, or it would be too awful for any of them to bear.

“But we should say some words, like we did for Mr. Keating. We owe Caleb that much.”

Javi stopped blowing on the base of the fire and looked up at her. “He went up to figure out where we are, to help us get home. Succeeding at that is what we owe him.”

“What was the last thing he said?” Molly asked. “Urss? Maybe he was trying to say Earth.”

“No,” Javi said gently. “It was just hurts.”

Anna pointed. “If we want to know what he said, then Yoshi has the right idea.”

They all looked up. Yoshi and Kira were using the forward inflatable slide to practice flying with the device they’d found, bouncing off the bright yellow plastic. Akiko watched from below, laughing like this was some kind of theme park.

Alien World. Fun for the whole family.

“I wish they wouldn’t make so much noise,” Anna said. “That foghorn thing is still out there, and it could be listening.”

“Another reason not to go exploring,” Molly said.

“But somebody has to check out what’s past the waterfall,” Javi said. “If those really were radio transmissions, it could be a scientific station!”

“Or maybe not,” Molly said. No one else had gotten anything but static on the radios. Yoshi’s ten seconds of beeping didn’t seem like much to go on.

“There have to be people here somewhere,” Anna said. “This place isn’t natural.”

Molly stared into the fire, which hissed with rain-wet wood. Part of her brain didn’t want to deal with theories and conjectures—she just wanted to grieve for Caleb. But another part of her wouldn’t stop puzzling it all out.

“What do you mean?” she asked.

“The animals are adapted to the weird physics,” Anna said. “The slide-whistle birds know how to fly in low G. And the shredder birds come looking for prey when they sense it. It’s like the creatures here evolved alongside this technology.”

Javi stared at her. “But how long does it take birds to evolve a new way of flying?”

“Thousands of years?” Anna said. “Millions? So either this technology is very, very old, or everything in this jungle is artificial.”

Javi tossed a stick into the fire. “Like, genetically engineered to mess with our minds?”

“No. But engineered for something. Which means there are engineers somewhere. We just have to find them, and beyond the waterfall is the obvious place to look.”

Molly looked out at the jungle. Had the two of them forgotten that someone had died out there last night?

She heard the trees creaking in the wind. Or maybe it was just her imagination and the crackle of the fire.

Anna was still watching Kira and Yoshi, who were high in the air, yelling at each other in Japanese.

“You want to go with them, don’t you?” Molly asked.

Anna nodded. “We need to know more about this place.”

“But every time we leave camp, something tries to kill us! The tanglevine. The shredder birds. And Caleb got killed by what? Gravity. A law of nature. And somewhere out there is whatever was making that—”

The foghorn cry came again.

This time it was loud, so close that the small hairs on Molly’s neck stood up straight. And it didn’t sound mournful …

It sounded angry.

“Molly!” Javi hissed, staring straight past her.

“Uh-oh.” Anna slowly knelt to pick up the gravity device at her feet.

Molly turned and saw the creature.

It stood on two wrinkled legs, a large flightless bird about halfway between them and the airplane. Its neck stretched into the sky, taller than an ostrich—maybe twelve feet high. Iridescent green feathers stood out from its body, like it was an angry cat with puffed-up fur.

Its head was the strangest thing Molly had ever seen. It seemed to be all beak, like one big razor-sharp scissor made of bone, interrupted only by a pair of beady red eyes.

She imagined the creature scraping that beak against a tree, leaving gouges in the bark, the edges growing sharper and sharper …

A cry came from Kira, in the middle of a bounce: “Abunai!”

The bird cocked its head, focusing one eye on her and Yoshi as they drifted down toward a petrified Akiko.

“Yep,” Anna said. “Dangerous.”

“Where’s Oliver?” Molly whispered.

Javi pointed. “In the plane.”

Kira and Yoshi landed next to Akiko and grabbed her hand, and together they jumped back toward the aircraft.

The giant bird ruffled its feathers and took a step toward them. Its powerful legs bent beneath it …

Molly’s mind spun. What if this bird was also adapted to low gravity? Yoshi’s sword would be useless in midair.

“Hey, bird!” Molly yelled, and the creature hesitated, pointing a baleful red eye at her.

She whirled toward the fire and grabbed the biggest burning stick she could see. Smoke and sparks spilled from the fire as she dragged it out. “Give me low G, now!”

“You got it,” Anna said, pressing buttons.

Weightlessness fluttered through Molly as she flung the burning stick. It spun through the air until it hit the edge of the gravity field. Its flight bent down then, but momentum still carried it onward. It struck the ground and rolled, smoking and sparking, almost to the giant bird’s clawed feet.

The bird hopped back from the stick, its talons leaving deep scrapes in the wet ground.

“Ready for heavy,” Anna said, and normal weight settled over them.

The bird stretched its neck forward and let out a long hiss at Molly, a long green tongue flickering from its maw.

“I think you made it mad,” Anna said.

Molly couldn’t argue with that. The bird was advancing now, its stubby wings puffed out even more, making it seem bigger, scarier. The feathers looked barbed at the end, like a shiny green mass of fishhooks coming straight at her.

She reached for another flaming stick.

“Please be afraid of fire,” she whispered.

Javi had lunged for the survival pack and was rifling around inside. He pulled out the survival knife and held it up before himself.

Those inches of steel looked puny in comparison to the charging bird. The heavy thump of its strides traveled through the ground and shook the soles of Molly’s feet.

This is how the jungle works, she realized. You stumbled around, having theories and solving problems, until something bigger than you came along.

Then you got eaten.

From twenty yards away, the bird took a mighty bound, its huge legs propelling it into the air. It arced toward Molly, a huge missile of razor beak and hooked feathers and muscle.

She held the burning stick in front of her …

A crushing weight descended on Molly, and the charging bird tumbled to the ground. It hit hard, rolling toward her in a cloud of dust and thrashing talons.

She tried to leap aside, but in the double gravity her feet felt dipped in concrete. She only managed a single step before the angry mass of claws and feathers swept past her. Pain blossomed across her shoulder.

The bird rolled into the fire, scattering smoke and sparks. It began to shriek like a pipe organ, a high-pitched version of its foghorn cry.

Then the heaviness lifted, straight from double gravity to almost weightless, and everything around Molly seemed to fly apart. Flaming wood exploded from the fire, along with clouds of dust, burned feathers, and scavenged clothing. The bird launched itself shrieking into the air, and Molly lofted backward in an aerial somersault. She caught a glimpse of Javi floating away, knife flailing blindly in the smoke.

“Ready for normal!” Anna’s voice came from the chaos.

Molly hit the ground as gravity settled onto her, landing with an oof. Smoking firewood was scattered everywhere, along with feathers and survival gear.

“Everyone okay?” Anna asked, her arms cradling the gravity device.

“I think so?” Javi was nearby, his eyes wide and searching. “But where’s the bird?”

Molly squinted through the smoke and dust—

The creature rose up from a huddle at the edge of the forest and cast an angry glare at them through its red eyes. It looked singed and ruffled, and it limped as it turned to face them.

But it still looked ready to fight.

Molly stood carefully. “You ready to hit that double gravity again?”

Anna nodded, but then another flutter of lightness went through Molly—and Yoshi went drifting past overhead. He landed between the scattered campfire and the wounded giant bird and drew his sword with a flourish, metal glittering in the sun.

The bird glowered at him a moment and let out the long, mournful foghorn blast of its cry. Then it turned and limped into the jungle, thrashing at the palm fronds with its claws.

A moment later it was gone.

Molly managed a smile, but then a wave of dizziness came over her.

She looked down at her right shoulder. Her sleeve was in ribbons, and a single deep cut oozed blood. Some kind of green liquid surrounded the wound. It was shiny, pulsing in the sunlight.

“That’s weird,” she said.

Anna came closer and stared. “Does it hurt?”

Molly shook her head. All of a sudden, nothing hurt. Not the cut or her bruises or her smoke-filled lungs. Suddenly, everything was soft and hazy, and she was so tired that she could barely keep her eyes open …

By the time she tumbled forward into the grass, Molly felt nothing at all.

The next morning at dawn they said good-bye at the stream. Yoshi’s plan was to follow it back to the waterfall, then go beyond. Not a terrible plan, Molly thought. But the beyond part sounded fuzzy.

Of course, everything sounded fuzzy today.

The cut on her shoulder still glowed iridescent green, as if the bird had left the glimmer of its plumage in her. No matter how much she washed it, the green didn’t go away.

But it didn’t hurt, not at all. In a way, the mysterious numbness was worse than pain would’ve been.

“It’s all here,” Anna said. She’d filled two backpacks with gear: knives, flashlights, fire starters, signal mirrors, and a first-aid kit. She, Yoshi, and Kira were taking the remaining flares and packaged food, which wouldn’t be needed at camp anymore.

The night before, Akiko had reluctantly agreed to lure another slide-whistle bird to its doom. Yoshi had missed with his sword, but Javi had caught the bird in a cargo webbing net. Javi himself had narrowly escaped accidental death by sword—bad planning on everyone’s part—but the bird had roasted up wonderfully with omoshiroi-berries.

Now that it was time to part, Akiko was crying and hugging Kira. Yoshi looked embarrassed, and Anna had the same blank stare she’d worn since Caleb’s death.

Not the most promising start to the trip, Molly thought. The cold wind hadn’t returned last night, and the glowflies were thicker than usual in the dawn light. The jungle buzzed like a broken neon light.

“We’ll be back in three days,” Anna said, and kissed Molly lightly on the cheek. “We’ll bring help. People who know how to fix that infection … or whatever it is.”

Molly smiled, wondering if Anna was really that confident, or if this was one of her white lies. Molly decided to lie herself.

“I know you’ll be back. You’ve only got three days’ worth of food, after all.”

“We should get started, then.” Yoshi shouldered his backpack, looking impatient to leave Akiko’s tears behind.

Anna picked up the new gravity device. “Take care of Oliver. And watch out for wounded killer birds.”

“Don’t worry about us,” Molly said as the sudden pulse of low G made her heart flutter. Then Anna, Kira, and Yoshi leaped gently up to the treetops, and a moment later they were gone.

Normal gravity descended, and for a moment no one said anything.

Molly broke the silence. “Maybe we all should have gone. Just to keep everyone together.”

“You aren’t going anywhere until that wound heals,” Oliver said.

“It doesn’t even hurt.”

Suddenly, Molly felt meek and useless for staying here instead of exploring. But the feeling only lasted until another wave of dizziness went through her, about the hundredth since the giant bird had left its poison in her blood.

What was happening inside her?

And how much longer did she have to wait to find out?