A report on the testing of Prussian cyanic gas on Russian prisoners of war, dated August 1941. Stapled to it—approval to advance to trials in the detention camps. Far more efficient than the exhaust-fed vans method employed at Chełmno, the approval concurred. Permission granted to begin construction on such facilities in Auschwitz and Bełżec for administration of Zyklon-B gas.

Human beings, gassed to death. For daring to be alive. And so many of them to be killed that the Nazis had to worry about processing the sheer volume of them, about efficiency.

With eyes burning, Daniel ran through the names on his list again. If the Nazis could have checklists for their brutality, then so could he. Every SS officer responsible—every one that he would kill. Gerstein, the camp capo who sat back, boots on the desk, congratulating himself on a well-run system as the people sent to Chełmno were slaughtered en masse. Kreutzer, the man who stole people from Łódź for his experiments. And should Daniel survive long enough, then he could work his way toward the names at the top of every transcript: the very leaders of the Reich.

Daniel barely felt his knees hit the floor before the bile was burning at the back of his throat, his tongue, his teeth. He only knew what he and Rebeka had heard in snatches of rumors and the smell of Chełmno, but that had already been too much. Had his parents died screaming, clutching each other as gas filled their lungs? Had Ari been amongst the ones who hauled the dead to mass graves before he too was killed? Maybe at least he’d gotten to squeeze their mother’s cold hand one last time as he lowered her into a yawning, hungry ditch—

Pale yellow spilled onto the wood, chunks of powdered milk in it. It only took one good heave to empty his stomach, but his body kept working, trying to wring the agony out of him. It didn’t know any better—didn’t know that what needed to be purged from his system was the entire world, that there was nowhere he could be safe from the poisonous potential of every human being alive. The Nazis in particular, to be sure; yet who were they but people who had been given too many assurances? Who’d never been challenged or had their voices silenced when they themselves were discussed?

He dragged himself back to his feet, clinging to the cheap plywood. Gerstein, Kreutzer, Himmler—where were they now? His hands raked over boxes, but he was uncoordinated, drunk with rage. Where were they now?

Approvals, so many approvals. For transfers, for requisitions. For experiments—so many experiments, some of them marked with Kreutzer’s name.

Gerstein. Kreutzer. Himmler. He’d etched their names into his heart with acid. Their poison would not spread.