Now Ehri smiled again. “Very good.” She gave a wave of her hand and the doctor scurried to a big metal door that had no business in a barn.

Mayu felt a chill move through her as the door creaked open. The room beyond was large and dimly lit.

“What is that smell?” Tamar asked. It was sweet, cloying.

“The sedative we use. It’s necessary to control the volunteers once they’re under the influence of parem. But they cannot do the work of creating khergud without it.”

The volunteers. He meant Grisha.

“We also use it on our khergud. They tend to get restless at night, since they have no real need for sleep anymore.”

What did he mean? Why would Reyem have no need for sleep?

The former dairy had been divided into three large areas. On the left was a kind of dormitory, a row of bunk beds and washbasins. Most of the occupants rested atop their blankets, their wasted chests rising and falling in rapid pants, their bodies little more than bones and waxen skin.

“How long—” Tamar swallowed. “How long can the volunteers be kept alive like this?”

“It varies,” said the doctor. “The older subjects have a harder time of it, but sometimes it just seems to be a question of will.”

A young man on a lower bunk lifted his head and looked at them with hollow eyes. He had flaxen hair, ruddy pink skin. He didn’t look Shu at all. Mayu nudged Ehri.

“Where do they come from?” Ehri asked.

“Oh, that’s Bergin. He’s from Fjerda.”

“And he came here willingly?” Tamar asked.

The doctor had the grace to look sheepish. “Well. Willingly enough after his first taste of parem.” He gestured to Bergin and the Grisha rose. He wore a kind of uniform—loose gray trousers and a tunic of the same fabric. Mayu saw desperation in his face, the same helplessness the other prisoners shared. But there was something else there too: rage. He was still angry. He was still fighting. “Bergin was a translator working for a shipping concern in Fjerda, but when his powers were discovered, he tried to flee the country. Our troops intercepted him and offered sanctuary.”

Fury flared in Bergin’s blue eyes. Mayu doubted the doctor’s story bore much resemblance to the truth. Bergin had probably been dosed by Shu troops and taken captive to serve as a “volunteer.”

“We’ve had him working on Locust.”

“Locust?” asked Tamar.

“The conversion from ordinary soldier to khergud is incredibly complicated, so we pair each volunteer with a soldier candidate for the duration. Of course, sometimes the volunteer dies before the work is complete, but we’re getting better at managing doses to prolong their lives.”