“We’ll go alone,” said Crier.

Storme shook his head. “Find the round door,” he instructed the two Automae. “Rescue anyone still alive. We’ll wait for you at the seastone.”

“Yes, sir,” they said in unison, and headed back down the corridor, silent as shadows.

Another explosion shook the corridor, closer now. Ayla squeezed Crier’s hand, reflexive, and tried to keep her expression steady when Crier immediately squeezed back.

“Very, very much time to go,” said Storme. “We’re not too far now. I’ll take lead. Bell, Rina, flank the girls. Neven, at the back.”

“Yes, Adviser Storme,” the humans said.

They’d only gotten a few more paces when the entire world broke apart.

The ground lurched beneath their feet, sending everyone sprawling, even as a great wave of heat billowed into them from behind. Head spinning, Ayla didn’t realize what was happening until Storme gasped, “That’s not us. That’s not us.”

BOOM.

This time, the walls rattled with the force of the explosion. Bits of rock rained down on them from above, and there came a second wave of heat, so hot Ayla thought it might singe her clothes. She struggled to her feet, spitting pink where she’d bitten her tongue. Her eardrums had popped; all sound was muffled. “If it’s not you, then who?” she shouted.

“Kinok,” said Crier, eyes huge. “He’s going through with it.”

“Going through with what?” Storme asked, coughing.

“Destroying the Iron Heart.”

BOOM. Ayla remained upright only because Crier was holding her hand. She staggered, coughing, the air thick with rock dust.

“Run!” Crier said. “Run!”

It was madness. Blinded by clouds of dust, skin burning with each new wave of heat, they ran. Ayla lost all sense of time and place, knew only that she had to keep chasing Storme’s voice. The heat seared her throat and lungs. At one point, she heard the tunnel collapsing behind them, a rockslide, stone crushing and scraping against stone—she tried to turn around, to see how close it was, but Crier tugged her ever forward.

At last, they emerged. The entrance blended seamlessly into the lichen-spotted stone of the mountainside. Ayla didn’t know exactly how much time had passed since she and Crier had found their way into the Heart, how long they’d been unconscious in that cell, but it was far past midnight now, the liminal blue-black hours just before dawn. The mountains were quiet with night, the only sounds being the singing of insects and the calls of faraway birds, farther down the mountain where green things gripped the rock. Then—BOOM. A roar of fire, a shriek of earth; Ayla saw a flock of birds take off, terrified, into the night sky.

“Look!” Crier said, pointing.

High above, at the peak of the mountain, a tower of smoke. Pale against the night, it billowed up into the stars. Endless. Ayla was struck silent, just watching. Her heartbeat was a riot; she could feel it pulsing in her dull, ringing ears. Sunlight had once streamed down onto the Iron Heart. Some crack in the mountain, a pinprick opening into that enormous cavern. Now, smoke rose up.