he Splinters on the altar shook with the thunder of approaching engines. The Ascetic’s nest trembled. A rib of broken tree shook loose from the roof and crashed down, scattering debris.

The old chraida dashed across the cable bridge and disappeared into the hollow. Left with no other escape, they scrabbled after him, fleeing back through the dank tunnel. In her haste, Phoebe stepped on something sharp and yelped as it cut into her shoeless foot. No time to see how badly she was injured—she could only hobble and try to keep her weight off it.

As she and Micah ran for the exit, they saw the heavy flap peel open. Three chraida finished securing the feeble Ascetic onto a cable zip line, then sped him away through the treetops.

“Hey! What about us?” Micah cried.

The kids rushed to the mouth of the hollow and looked out upon the chraida village. Searchlights sliced down through the darkness, reflecting off metal leaves and casting a million fragments of wild light. A torrent of wind parted the treetops to reveal Aero-copters, their onyx bodies blotting out the stars. The twirling blades embedded within their frames chugged like a collective heartbeat. Their bases irised open, and hydraulic arms bearing shielded platforms emerged and maneuvered through the canopy like the heads of a hydra.

“We gotta split!” shouted Micah.

“How?”

“There!” He pointed to a wind-blown zip cable that ran down and out of sight. He pushed past her and tested the line with a few hard tugs. “Come on!”

There was commotion in the village as chraida tried to fend off the invaders, leaping at the aircraft, casting nets, and hurling crude weapons. The Aero-copters’ articulated platforms hissed open to reveal cruel cannons. In a blinding flash, the guns whirred out a spiraling shower of white rounds.

Phoebe looked away, but she could not avoid the screams.

Then another desperate cry pealed out behind them.

“Help!”

She recognized the warbling voice. “Dollop?”

“Nothin’ we can do for him now,” Micah said. “We gotta—”

But she had already turned to limp back through the tunnel despite his furious protests. Dollop had information about the Citadel. He was her best shot at finding out where Goodwin had taken her father.

As Phoebe rushed into the Ascetic’s suspended nest, something smashed against the tree outside. The whole cocoon swung wildly, like a birdcage struck with a sledgehammer. She staggered, clinging to a beam for support. Debris fell around her. Cables snapped and sang.

“What are you doin’?” hollered Micah. “This thing’s gonna fall!”

“H-here! Under here!” Dollop’s desperate voice squeaked.

Beneath the crumpled altar they could see a slim metal arm. She pulled and shoved at the slab, but it was too heavy for her. Aero-copter blades boomed all around them, and Phoebe felt her blood thrumming.

“Help me!” she screamed.

Micah ran to her side. Together, they strained to lift the massive altar. It only raised a couple of inches, but that was enough. Dollop yanked himself free and skittered to the far end of the demolished den. He hesitated, staring back at the kids in wide-eyed terror, unsure of what to do.

“F-f-follow,” he stuttered at last, and then vanished.

The word struck Phoebe. It was the same one that had beckoned her into the train tunnel. She felt a surge of exhilaration. No time to linger.

They booked after Dollop with Phoebe hobbling as fast as she could. The little creature wormed his way through a gap in the woven floor and into a crawl space so tight they had to wriggle along on their bellies.

It wasn’t long before Micah stopped, blocking the way.

“What is it?” she asked.

“Look.” He squeezed over so that she could see. “Think you can make it?”

The crawl space ended in the base of the nest. A twanging cable stretched over to the inner wall of the tree five or six yards away. Dollop pulled himself across the line, grabbed on to rungs carved in the tree’s surface, and then rapidly climbed down into the darkness below.

She and Micah had to catch up or lose their only guide.

“I’ll go first,” he said. “Wrap your arms and legs around it and hang underneath, then you can inch across and—”

“I get it. I did this a thousand times in gym class,” she lied.

“All right. Don’t get all snippy.” He grabbed on to the cable and slung beneath it, scooting his way across like an inchworm. He made it look easy.

Now it was her turn. She held on and let gravity swing her below the line. Her legs were stronger than her arms, so she favored them, locking her ankles tight. Phoebe felt her arm muscles tremble with exertion, but she ignored it and focused on moving as fast as she could. Within a minute, she was at the wall and easing onto the notches cut into the rough tree.

That wasn’t so bad, she thought.

Then her foot slipped. Micah shouted. Adrenaline flooded her body. She clung to the cable, flailing and kicking her legs wildly as she tried to regain her foothold, but the rungs were slick with sap. Phoebe wedged her shoe into a crevice in the wall and, using that as leverage, she pulled herself close enough to find a solid grip. She let go of the cable and clutched the rough carved handholds for dear life.

“You okay?” Micah called up.

She realized with a pinch of embarrassment that her skirt was whipping all over the place, and Micah was right underneath her. Nothing to be done about that now.

Slowly, one notch at a time, they climbed down the wall. She tried desperately to not think about falling, and instead concentrated on maintaining her grip. The adrenaline was wearing off, and now she was feeling spent and shaky. Every time she forced her uncovered right foot into the grooves of the wall, a flaming dart of pain shot up her leg.

Micah, on the other hand, was climbing down at a steady clip. He was used to running and scaling trees, twisting ankles, and getting beaten up. The kid was tough for his age—she could see that now. But not Phoebe. Had she ever felt exhaustion like this in her entire life? Did she ever have to strain for any reason at all? Of course not. She had servants like Micah to do everything for her. She gritted her teeth and bore down into the slick handholds.

Micah is right, she admitted hopelessly. I’m just a stuck-up, pampered little brat.

A crash overhead tore Phoebe from her self-pity. Great sheets of falling metal bark sheared through the Ascetic’s nest, smashing it apart and severing cables with a tumultuous twang. The mummified bodies, the dainty teacups, the shattered altar—it all came spiraling down. The tree shuddered as debris ricocheted off the walls and cascaded in a cloud of shrapnel. It plunged into the darkness and hit the bottom with a violent clang.

Her breath was coming in short rasps now. She kept climbing, rung by rung, each step a new agony. Phoebe needed ground beneath her again.

“Come on!” Micah shouted. She saw him disappear into a hole in the wall. An exit. Almost there, just another few rungs.

A sudden stillness settled around them, and she felt a change in the air pressure. A few motes of that gray powder drifted around her as she took a step down. Then an unfathomably low tone rolled out of the darkness below, an elemental note groaning from deep within the ground. Another rung down. It was the primal song of the forest, that strange, organlike harmony they had heard blowing out of the hollow trees.

Last step.

She reached for the foothold, but her toes did not find it. An explosion of wind surged up and lifted her like a feather. Phoebe was weightless, floating. She clung to the rung and tried desperately to pull herself toward the wall. Within the roaring wind was a deluge of gray dust, rippling past her, trying to drag her away. She buried her nails in the wall and fought against the flood with all her might, flapping upside down like a sail in a hurricane.

Phoebe had a flash of her inevitable fate—she would be sucked up into the tree and ejected out the towering top. And then, the fatal, crushing fall.

She closed her eyes and prepared for the end.

Hands grabbed her wrists. She was pulled against the tide. Micah hauled her into the safety of the tunnel, and they collapsed. The wall of gray dust rushed past as they lay there, shaken. Phoebe was seized with panic, gasping for air. She stared at Micah, not quite seeing him, not quite believing.

“You’re okay,” he said. This time it wasn’t a question, more like he was reassuring himself.

As the howl of wind died, they heard Dollop’s distant footsteps and snapped alert. In seconds, the kids were back on their feet and stumbling after the little creature. She activated her Trinka to light the way.

They followed through hollow branches that led from the main trunk like a network of sewer tunnels. Sap gummed up around their feet, making progress slippery and slow, but soon they found their guide scampering down a hole in the floor. She aimed her Trinka into the cavity and spied Dollop crawling straight down a vertical pipe. He was spread-eagled, lowering himself carefully with his extended arms and legs.

Phoebe tried to imagine herself doing the same thing, holding up her entire weight and inching down, down, down to who knew what. Something collapsed within her, as if her insides suddenly deflated and shrank away.

“I can’t,” she confessed. “I can’t do it. I can’t go on.”

“You have to,” Micah insisted. “You just gotta squeeze against the side, with your back to the wall and feet out. Take it slow, ease down bit by bit.”

She had nothing left. No strength to go on and yet no will to resist. All she could do was offer a weak nod and lower herself into the hole. With her legs crunched against her chest, she pressed hard against the side with her feet and reeled at the pain. She relaxed her muscles and slid down a few inches, sloshing down the slick tube like a clog in a shower drain.

It was misery, and her legs were killing her. But she had to.

Micah said she had to.

He climbed in after her, and they scooted down inch by torturous inch with no sense of how far they had to go. A rumbling explosion shook the branch like a gong. Phoebe slipped down the tube and tensed her poor wobbly legs, barely managing to stop. She felt her grip weakening. There was only so much she could take. She started to let go.

Then there was a sloppy struggling in the pipe up above. Gobs of goo splatted down on her.

“Look out! I’m—” was all she heard.

Micah crashed on top of her. Phoebe tore loose and plummeted too. A thrashing knot of limbs and screams tumbled into Dollop.

They all fell.

The pipe opened up, and they were launched out into the forest. The trio crashed through foil leaves, snapping past metal branches. They plunged into a tangle of chraida cables, and Phoebe grabbed fistfuls in a desperate bid to slow her descent. She clung and fell, then held on tighter and dropped some more. Fully ensnared now, her momentum slowed. She flipped and turned and grappled in the mess of lines as the blurring ground spun into view.

The cables stretched and creaked, but held, and at last she eased to a stop ten feet above the forest floor.

Then Micah shot out of the darkness, swinging from a loose cable like a crazed orangutan. He zipped past her, let go of the line with a flourish, and landed hard, tumbling over and over in a chaotic somersault. He rammed into a silver sapling with a hollow thud.

Far above, through the maze of angular branches, searchlights still scanned the canopy. The rumble of the Aero-copters was like a distant storm.

She squirmed to untangle herself, then hung down from the lowest cable and collapsed roughly to the ground.

Micah was already up and dusting himself off. He caught sight of her and laughed. “You’re a mess.”

She got up on her elbows and brushed her tangled hair from her face. They were both coated in splatters of viscous sap and dusted in gray powder.

“Where’s Dollop?” she croaked.

As Phoebe started to pull herself to her feet, she grazed something warm in the underbrush. She recoiled and used her Trinka to see what it was.

“Oh no!” she gasped.

There, among the fallen leaves and tire tracks, was a slender metal limb. Dollop’s severed forearm. She covered her mouth. Micah came up beside her to see, and a grim expression settled on his blunt features.

“Poor Dollop,” she whispered.

The forearm twitched. The kids recoiled as it slithered off, bumping into roots and foliage to find other wriggling pieces. They fused on contact to form an elbow and shoulder, then hopped away. Astounded, Phoebe and Micah followed the limb over to a slipshod Dollop, who was partially reconstructed and hobbling as fast as he could. The rest of his parts clumped and stuck to him until he was complete and running away at top speed.

“Dollop, wait!” she cried.

The terrified little creature skidded to a stop and looked back, his luminous eyes glinting and reflecting back at the kids in the dim light.

“Please, we need your help. The Citadel, we—”

An engine growled nearby. They looked through the trees—approaching headlights, lots of them. The Foundry was combing the forest.

When they looked back, Dollop was gone. Her heart fell.

“Come on, Plumm. Forget him. We gotta go!”

Micah pulled her sleeve down to cover the glowing Trinka, and they sprinted away from the lights slashing between the trees. The rumbling hum was growing louder, accompanied by the crunch of wheels on metal foliage. More searchlights up ahead. Micah looked around in a panic. A fallen log lay decomposing and rusted in the undergrowth nearby. He shoved Phoebe inside the decaying pipe and crawled in after her. Then he gathered up arms full of leaves and debris and used them to cover up the hole.

It was black inside, but flaring light sliced through cracks in the log, so the kids peered out through the slits. Heavily armed vehicles rolled past, their headlamps revealing a platoon marching among them. Wind blasted and shook their cover as an Aero-copter shuddered past.

Had they left any footprints? Would their tracks be easy to follow, or would they be lost among the fallen foil leaves?

Through the glare, Phoebe was able to make out one of the figures. He wore mottled gray-and-rust-colored army fatigues with bandoliers of magazines strapped across his armored chest. Beneath the helmet and gleaming face shield, she recognized that vacant, haunting expression.

These were Watchmen soldiers.

After what seemed an eternity, the lights and vehicles moved away, growing fainter and fainter until they were gone.

The forest returned to silence. The kids lay in the dark for a long time, their minds reeling and their bodies numb.

“Micah,” Phoebe whispered.

“Yeah?”

“The chraida…We brought the Foundry right to them. They…they died because of us.”

He yawned and she could smell his sour, hungry breath. Her eyelids were sticky with sweat and getting heavy.

“It’s their own dumb fault. It ain’t like we asked to be tied up and taken to their stupid village anyway.”

“But all of those innocent people.”

“What people? All I saw was a bunch of monkey machines that wanted to kill us.”

“You know they’re not machines. You saw them.”

“They shoulda known better than to nab us,” Micah said.

“That doesn’t give the Foundry the right to murder them.”

Did her father know what the Foundry was doing to the chraida? He couldn’t even bear to squash a cricket—instead, her dad would catch it in a jar and set it free outside. He would never stand for this.

She couldn’t fight off fatigue any longer. Sleep was taking her. Their hiding place was painfully uncomfortable, but her body demanded rest. The Chokarai forest all around them was quiet as Phoebe drifted off.

But her head echoed with the screams of dying chraida.