In the end, it was simple. Mr. Gerrard was like any other bully. He didn’t expect anyone to fight back. And he certainly didn’t expect to feel the sharpened blade of a carving knife slicing across his throat as he sat at the dinner table. Dexter had gotten up to clear the dishes, as he always did. He pulled on a pair of rubber gloves, slipped the knife out from under the dish towel where he had left it that afternoon, and looked right into Jack’s eyes as he stepped up behind Mr. Gerrard. This is for you, his look said. Because I love you and because this man is never going to hurt you again. He gave Jack a nod that said, Look away just before he cut Gerrard’s throat. Jack understood.

Dexter cut deeply and stepped back quickly. Gerrard hardly made a sound. He tried to turn in his chair but slid to the floor. Not until his head hit the tile with a thud did his eyes catch sight of Dexter. “That was for Jack,” Dexter said as the ten-year-old left the room. And maybe Patton was right. Maybe he was an emotionless robot. Because, as Mr. Gerrard breathed his last, a look of surprise and incomprehension still on his face, Dexter felt nothing.

Patton started awake as the plane banked toward its final approach to Heathrow. She had not meant to fall asleep. In the next cubicle, Nemo was just finishing his tea. She flashed back over what had happened since yesterday morning and any hint of an appetite left her.

“Any luck?” said Nemo cheerfully, nodding to the notebook on Patton’s lap.

“Maybe,” said Patton. She had relied on vague memories of a smattering of German picked up when she had been stationed in Stuttgart and the tourist phrase book they had bought at the airport. “I found a lot of phrases that didn’t work because they encoded individual letters as themselves.” She hadn’t explained this aspect of Enigma to Nemo before, but she plowed on. “ ‘Project Alchemy Completed,’ ‘Project Alchemy Abandoned,’ ‘Project Alchemy Failed,’ none of those worked.”

“So what did work?”

“It seems pretty unlikely that this is a good crib, but the only guess I had that passes the test is ‘Project Alchemy Successful.’ ”

“If that’s right, it would explain why people are willing to hire me and shoot you in order to get that paper.”

“Yeah, but it’s ridiculous,” said Patton. “You can’t turn lead into gold, everyone knows that.”

“Two hundred years ago everyone knew you couldn’t fly, yet here we are.”

“You told me you thought it was nonsense—the idea that the Nazis mastered alchemy.”

“I do think it’s nonsense. But it doesn’t matter what I think. What matters is what Fritz and Franz and the people who hired them think.”