What the …” Javi started.

He was still climbing, wafting up toward the white sky. But he had no sense of motion or momentum. It didn’t feel like flying, exactly, more like the ground was falling away. It was as if the crashed plane and the jungle itself had all been fake, a film set that was dropping away beneath him, leaving him here, suspended in midair.

He stared down at Anna and the two girls, who stared back up at him. The device still flickered in Anna’s hand. The air seemed to ripple around her.

The machine was doing this—whatever this was. Javi’s guts felt suspended in his body. His clothes didn’t hang on him. Everything floated together, weightless.

Was he ever going to stop climbing? Or would he just go up forever until he disappeared into the white cloud above?

No. Javi realized that he was slowing at last, then falling toward earth again. Though it felt more like the other way around—the ground was rising up to meet him, as slow and stately as a giant ship easing into port.

Down below, Kira was floating, too, only a few feet in the air. Her sketch pad and the survival knife hovered beside her, and the bottom of the inflatable slide was wafting up.

Anna’s long hair was floating wildly around her head. It was like gravity had been canceled. Or at least dialed way down.

Which meant that when he hit the slide again, Javi would bounce up again. Not good.

As he drifted downward, Javi readied himself to crumple his legs. Like on a trampoline, he would stifle all that energy with his own body.

But the moment before he hit the inflated plastic, a completely different idea—a wild, irrational one—overtook him.

Maybe he should go higher.

His first bounce had taken him almost to the tops of the trees pressed in tight around the airplane. They hid the rest of the jungle, and anything else that might be out there. But now Javi had a chance to see beyond them, from a bird’s-eye view.

More than anything else, he wanted to know what on earth was going on.

So when his feet touched down, he bent his knees, then launched himself upward as hard as he could. Straight into the sky.

“What are you doing?” cried Anna.

“Taking a look!”

Javi shot higher, until he was above the trees, staring down at the broken plane laid out across the jungle. He saw how its spine gaped open as if a giant claw had traveled down it, how the wing on the far side lay snapped in two.

He gazed back along the trail of the landing path. The first marks of the crash were miles away, where the plane’s belly had sheared off the jungle canopy. A little closer were the trees bent by its passage, and finally the splintered remains of those it had ripped straight through.

The jungle was so thick. Cutting through a mile of that dense growth, the plane should have been torn to pieces. Just like it should have tumbled out of control from the sky, instead of coming down in a straight line.

But something had protected it.

Javi looked around—nothing but jungle in all directions, though the mist made it hard to see very far.

He heard a rumbling, though. He’d felt it down on the ground, a low, persistent noise that seemed to come from everywhere. But from this height Javi could hear where it actually came from—in the distance off to the left of the crashed plane.

It sounded like a waterfall. Which meant there had to be water around somewhere.

As he began to descend again, Javi felt a sudden jolt of panic. If gravity came back now, the bouncy slide wouldn’t be enough to save him. His legs would break, and his guts would turn to jelly.

Why had he jumped so high?

“Don’t panic,” he told himself, and surveyed the jungle one last time, to make this trip into the sky worthwhile.

Way out there, he saw something beyond the trees. At the horizon, in the direction the plane was pointed, something flat and formless glimmered.

But a moment later Javi was too low to see anything but trees … and birds.

Screeching like demons, a flock was skimming through the jungle canopy. They were small, bright green, and formed into a tight pack. They seemed to ripple among the branches, the sunlight glinting from their long, sharp beaks.

They were coming right at Javi.

Maybe he should try to scare them off?

“Shoo!” he shouted, waving his arms as he slowly fell.

But the birds kept coming, and he barely had time to cover his face before the whole flock shot past in a roar of feathers and shrieks.

“Ahhh!” he yelled, feeling slivers of pain open up all over him, like a dozen paper cuts had appeared on his skin. Why were birds attacking him?

Javi opened his eyes after the fluttering had passed. His shirt was ripped and torn, and blood seeped through in a few places. The backs of his hand were bleeding, too—he’d covered his face just in time.

He was still falling toward the ground, but not fast enough. The flock was whirling around again, coming at him.

“Help!” he yelled.

Anna was looking up in horror. She grabbed one of the floating pieces of metal from the wreckage pile—the emergency door. It had weighed maybe sixty pounds, back before gravity was optional. But Anna sent it hurtling toward him like it was a cafeteria tray.

What was he supposed to do with it, though? Use it as a shield?

The birds were closing in when Anna shouted, “Third law of motion!”

Javi tried to think. Every action has an equal and opposite reaction? Like jumping forward from a skateboard, and it rolls backward …

Just in time, he understood. He grabbed the emergency door as it passed, which sent him spinning, then hurled it as hard as he could straight up into the air.

Which sent him careening straight down toward the ground.

The flock of birds shot past again but most of them missed, passing overhead. One bird crashed satisfyingly into the door, and a floating cloud of feathers exploded above Javi.

The flock was already wheeling around again. But he was descending much faster now, thanks to the door.

Below him, Kira had stuck the survival knife into the ground. She was clinging to it with one hand, and to Akiko with the other.

As Javi hit the slide, he imagined himself bouncing back up into the air and being torn to pieces. But then Anna did something with the device …

Full-strength gravity hit like a punch in the gut, and Javi flopped back onto the inflated plastic. There was a clatter as the floating piles of water bottles, survival tools, and wreckage all hit the ground together, along with grunts from Kira and Akiko.

“Incoming!” Anna cried out. “Get under the slide!”

Kira and Akiko were already crawling under cover. Javi tried to scramble off the plastic, but his muscles felt weird and wobbly. He slipped to the ground just as the roar of the flock filled the air above him …

… and kept going.

He looked up and saw the birds disappearing into the trees.

“Javi!” Anna screamed. “Get under here!”

He shook his head. “They just—”

“Door!” she cried, as a huge metal crunk came from behind Javi, making him leap into the air.

He spun around to find the emergency door crumpled on the ground. It had gouged a fat hole in the dirt, maybe five feet from where he stood.

“Whoa,” Anna said as she emerged, staring at the door. “I forgot about that when I turned the gravity back on. Are you okay?”

Javi looked down at himself. He was covered with tiny cuts, but none of the razor-sharp beaks had found a vein. Just lucky, he supposed. And he’d been lucky with the falling emergency door, too.

But the prospect of being crushed wasn’t why his knees were shaking. What was making Javi feel sick was the phrase that Anna had just uttered so casually.

When I turned the gravity back on.

What was that thing?