“I trust you,” Crier breathed.

And I will trust myself, Ayla thought. I have to.

Crier’s heart, unlike the Automa girl’s heart from the memory of Siena, was beating. Ayla could hear it ticking like a clock, could see the faint vibration of each pulse. She saw where the tiny gold and copper veins fed into it. This was the challenge: fitting the new heart into Crier’s chest at exactly the right angle, reattaching the veins and vessels. Ayla remembered the sound she’d heard in the memory, like a latch clicking into place.

The blue heart rested on the flagstones beside her, nestled in a scrap of cloth. Ayla raised her head to look at Jezen. The Midwife’s eyes were an unusual green, like chips of emerald.

It was time.

So carefully, shifting her knife only the tiniest fraction of an inch each time, Jezen began to cut Crier’s heart out of her body. Ayla watched, unblinking, as Jezen severed the veins one by one, detaching them cleanly from the surface of the heart. The veins seemed alive, moving independently of each other, like wiry, hair-width blades of grass swaying in a nonexistent wind.

Jezen severed the last vein. Crier’s face smoothed over instantly, her whole body going lax. Ayla swallowed hard, trying not to panic. This was what it looked like when Crier died.

But it was temporary. Ayla picked up the Tourmaline heart and held it in both hands, waiting, as Jezen lifted Crier’s old heart out of her chest. There was the familiar hollow space, the pocket left behind. Ayla shoved aside her panic, took a deep breath, and let instinct and memory take over. She turned the blue heart in her hands, matching the angle to what she had seen in Siena’s mind. She remembered the positioning of the alchemical symbols: fire, water, earth, air, gold. Here, just like that. Then, without hesitating, she lowered the Tourmaline heart into the hollow in Crier’s chest. She pressed it into place, feeling Crier’s inner workings flutter beneath the pressure, flexing and shifting to accept this new object. Maker’s iron, as the bandits in the woods by the River Merra had said. Black magick, that. Iron that moves and breathes. She held out a hand and Jezen passed her the knife, and Ayla slid the tip of the blade under Crier’s veins, guiding them into place. The etchings on the surface of the heart weren’t just letters. They were a map. The tips of the severed veins matched perfectly with the points of each letter, latching on. Stilling once more.

Ayla pulled the knife away. There was a faint, almost inaudible sound. Like a latch.

Nothing happened.

Ayla sat back on her heels, waiting. For Crier’s eyes to open, for her chest to rise and fall again.

Nothing.

“Ayla,” Jezen said.

“No,” Ayla said, louder. Think, think. Why hadn’t it worked? What was different? What would it take to breathe life into this heart?

The only other time she’d seen Tourmaline come to life, it had been in the hands of a boy with a hammer. He’d been making a bomb. Ayla remembered the symbols he’d etched into the surface of the bomb, ready to be activated with a drop of blood. Fire, saltpeter, sulfur. Mortar. Salt. And she remembered what Lady Dear had said, on that sunlit afternoon in the palace at Thalen.