For a few moments, there was a muffled quiet, then the sound of the cell door being shut, and once again the footsteps, slower this time, their noise clacking and reverberating against the sides of the corridor. Lockhart wanted to run to his own door, and shout out some words of encouragement to Nicolas, but it would be pointless and might even serve to put him in a similar situation. Instead, he listened to the sound dwindle, until the corridor lay guiltily silent.

Lockhart turned his head to the wall, now robbed of its voice. Perhaps the voice would return, but he doubted it. He clenched his right fist and repeatedly hit the wall with its side, allowing the roughness of the stone to scratch and graze him.

MITT. What—or who—was Mitt? Perhaps it was the beginning of a word—Mitt…something. Was it the name of Nicolas’s source? He could be anybody—an official, an SS officer—but whoever he was, if indeed he was the source, he knew something that he couldn’t keep quiet, something so dreadful that his conscience was troubled enough to tell a Russian agent about it. And that something was, apparently, a gas that could kill millions.

Or maybe it was lies, the fantasy that Lockhart had initially felt it to be. But why make up such a story? And the name—sarin—sounded too specific to have been made up by a partially insane, torture-racked Russian agent. Gas had been used in the last war, so why not in this? And technology would have moved on a lot since 1918—perhaps it was possible that the Germans had formulated some horrific chemical that could eradicate the populations of whole towns, whole cities. Lockhart breathed out. There were too many questions: Where was it? How was it to be used? Had it already been used?

The answer to one question, however, was now clearer than before: he had to continue. It wasn’t just for Anna and Amy, but for—Christ, was it really true?—the whole war effort, the whole of Europe. It seemed ridiculous. It occurred to him that he might be floating on a giant swell of lies—his family could be dead, and sarin could simply be the product of a lunatic imagination. But then the whole war was the product of a lunatic imagination. Anything was possible. What didn’t seem so possible, thought Lockhart, was how he was going to find out more and how he was going to tell the Allies. There would be a way, but right here, right now, his options felt just a little limited. He smiled wryly at his own understatement.

Exhausted, Lockhart drifted into a half-sleep. Although his body demanded it, something kept him from going fully to sleep. Mitt. No, it wasn’t possible, he told himself. It was just hope talking, cruel hope.

A few hours later, the sound of boots once more invaded the still corridor. Lockhart felt his pulse quicken as he heard the rattle of keys unlocking the cell door. Müller entered, now wearing the black uniform of an SS gruppenführer—three white braid oak leaves on each collar, a Knights Cross at his neck.