She tucked her wheat-blond hair up into a stern chignon, then dabbed two circles of rouge on her cheeks. Lipstick was too great an indulgence, and drew the wrong kind of attention, she’d learned. She needed to look presentable to keep her position, but more or less invisible otherwise. It would come in handy when she needed it most.

Fully composed, she grabbed her identification badge, the one stamped with the swastika and laurel wreath, and called goodbye to her mother as she slipped out the front door.

It was only a short walk to work, but the early autumn air carried the scent of something dangerous in it, something smoky. Not the smell of burning leaves—too early—or the sharp, too-sweet stench wafting off of Niederhagen KZ. Something darker lurked in that scent, blowing in from the west like bad luck. It sent an uneasy trill down Ilse’s back and quickened her step.

Ilse reached the entrance and flashed her identification at each successive tier of guards. Crossed the drawbridge, newly repaired, its stone masonry scrubbed raw. Entered the castle with its freshly exposed face, like a healthy spa peel in Switzerland. Gathered her overstarched lab coat and gloves from her locker and pulled them on. Then clicked her way toward Dr. Kreutzer’s laboratory with a secret smile.

Ilse was always smiling in secret, because Ilse, unlike the earnest, sour-faced Nazis around her, was a spy.

She didn’t like to dwell on it—didn’t want it to seem like she was bragging—but Ilse had infiltrated the very highest echelons of the Schutzstaffel’s administration at Wewelsburg. She assisted Kreutzer with his research and coordinated information across countless other departments, keeping the cogs of the SS turning properly.

For now, for now.

What the SS didn’t see beyond Ilse’s cool façade was the catalog she was building inside her head, the one she knew would someday aid the resisters in tearing it all down, stone by stone. Knowing this role she was soon to play—as soon as she figured out how—made each banal horror a little more bearable, made each cruelty she assisted in a little less cruel. Someday, she would do the right thing and turn over everything she knew. Someday, her trap would be sprung.

Once she knew what trap to set, that was. But that could all come later.

“Ilse, darling. You’re just in time.” Herr Kreutzer was waiting for her at the entrance to the laboratories. “We have a new arrival to assess.”

Ilse’s stomach curdled, knowing the sort of deliveries the Herr Doktor usually took, but she offered a polite nod.

“If it proves to be what I think it is, then we must move forward quickly. Come, let’s find out.”