“No,” he said. “At the site, I sensed I was being watched. I needed to do lab work and examinations, but I didn’t dare do them there. So I came back here. There are colleagues at Humboldt and at the Free University who have let me use their labs. I’ve been sleeping in the office of a colleague who is on leave and using the shower in his chemistry lab.”

“Why not just go back to your own lab at Heidelberg?”

“A bit of a ruse to throw off anyone who might be interested in what I’m doing. I had some odd feelings while I was at work, and I’ve found that when you think you’re being watched, you usually are.”

Fischer took them outside the terminal, where he hailed a cab that took them to the Hotel Adlon Kempinski. While Sam checked them in, Remi took in the beauty of the hotel—the ornate carpets, fine furniture, vaulted ceiling—but she also noticed that Albrecht Fischer’s eyes were moving constantly, scanning the steady stream of people coming and going through the lobby. He was agitated, impatient, and, at the same time, there was something else. He seemed to be afraid. Sam sent the bellman up to their room with the luggage, then rejoined Remi and Fischer. “Shall we go up?”

Remi shook her head. “I think we’d better go see what the good professor has been working on.”

Albrecht brightened. “Yes, please do. I know you’re probably tired from all the travel, but I’ve been keeping myself quiet about this until I’m half mad. And the lab isn’t far.”

Sam and Remi exchanged a glance, and Sam said, “Then of course. Let’s go.” They stepped outside, and the doorman signaled a cab and opened the door for them. Albrecht waited until the door was closed to say, “Humboldt University, please.” The cab let them off only a few blocks away at the statue of Frederick the Great in front of the main building of the university on Unter den Linden.

They walked quickly into a building that seemed to be all science laboratories—doors with smoked-glass windows with numbers on them. The ones that were open had young people inside, wearing lab coats and wandering among black boxes with screens, stands that held chemistry apparatus, and counters with centrifuges and spectrometers. As they passed, Sam kept looking into each lab. Remi took Sam’s arm. “I know you’re reliving the high points of your college years.”

“What do you mean?” asked Albrecht. “I thought all American students did was drink beer and go to parties.”

“Sam went to Caltech. They worked in labs, then drank beer and went to parties.”

“I was just thinking about some of the people who went to this university. There was one student who was promising—a kid named Albert Einstein.”

Remi said, “And before him, Hegel, Schopenhauer, the Brothers Grimm . . .”

“Today we’re going to rely on Remi’s specialties,” said Albrecht. “A bit of history, a bit of physical anthropology.”