The following morning, Shein was gone again. But Logan no longer saw this as his concern. Never mind appearances, this guy was obviously as capable of fending for himself as anyone he’d ever known.

Anyway, he had other things on his mind. This was the day he was to visit the building in which Paul Ehrlich had conquered syphilis, now a cancer research center. Its directors had taken advantage of their proximity to the conference to arrange a tour and various sessions.

Logan didn’t have much interest in the topics to be discussed, but he had another reason for coming. This was a pilgrimage. He was coming to this place as a wide-eyed tourist and unembarrassed fan, the way others, back home, visited Elvis’s home at Graceland; imagining, like them, that he might pick up some small sense of what made the great man tick.

The chartered bus from the convention center deposited Logan and two dozen others before the building shortly before eleven. Instantly, he was disappointed. From the outside it was curiously unimpressive; a massive, ivy-covered cube of gray stone fronting a narrow street (renamed the Paul Ehrlich Allee after the war) and adjoined on either side by buildings of nearly identical size and shape. The only sign of its remarkable history was a tiny metal marker in the corner.

Entering, Logan was further disheartened to note that the interior seemed to have been lately refurbished; incongruously, the large reception area was filled with the kind of ultramodern furniture Logan had come to associate with eager-to-impress Park Avenue physicians like Sidney Karpe. Now it was the few remaining traditional touches that seemed out of place: A pair of large, ornate Oriental vases, filled with peacock feathers. A stately portrait of an elderly woman in turn-of-the-century attire—identified as the wife of the home’s original owner and Ehrlich’s benefactress. An alabaster bust of the scientist himself on a marble plinth, his name and the dates 1854–1915 inscribed on the base.

The visiting doctors and researchers were greeted by an earnest young researcher who identified himself as the assistant to their host, the center’s director. In impeccable English, he gave a brief rundown of the kinds of work being conducted here. As they would shortly see on their tour, the Institute’s labs were state of the art; less than two years before, the upper floors had been gutted and rebuilt. Lunch would be served at the conclusion of the tour, with the featured speaker, the center’s research director, speaking over dessert and coffee. He and his colleagues were, of course, very much looking forward to questions, remarks, and observations from the distinguished guests.

Inwardly, Logan shuddered. This had nothing to do with the magical place that had stirred his imagination all those years before. From the sound of it, even those who worked here had little appreciation of the extraordinary things that had once been said and done within the walls; no sense that they were inheritors of one of the most remarkable research legacies in the history of science.

Perhaps it would have been wiser not to come; leaving the illusion, at least, intact.

By the time, half an hour later, they were midway through the tour, he was sure. Logan was ready to bolt the place—and would have, if he’d had any idea where, in this quiet, dull neighborhood, he could grab a cab. The labs the young researcher was showing off were identical to those Logan had worked in himself: in fact, the flow cytometer of which he seemed so proud—a machine that shoots cells into the path of a laser beam so they can be studied individually—was the model the ACF was about to retire.

As the group moved en masse up the stairs toward the top floor, housing yet another set of labs, Logan slipped down the stairs, heading for the reception area. He’d been sipping coffee throughout and it had caught up with him.

“Pardon me, do you speak English?”

The receptionist cast him an impatient look. “Yes, of course.”

“Can you tell me where the bathroom would be?”

She nodded in the general direction of the front hallway. “Go through there and down the stairs. Then straight on to the next room. Turn left. And turn left again. You will see it on the right.”

He was certain he’d done precisely as told—which is why he was confused to suddenly find himself in a narrow corridor that dead-ended against a wooden door.

Was this what he was looking for?

Tentatively, he pushed the door open—and instantly knew he should close it again. Wooden stairs led downward into the basement. But, after a moment’s hesitation, he flicked on the light instead. Moving quietly, feeling an almost perverse sense of exhilaration, he moved down a few steps and bent low to peer beneath an overhang.

What he saw convinced him to go the rest of the way down: vintage lab equipment, the kind he’d seen before only in photographs, neatly arranged within old glass-fronted oak cabinets lining the walls.

Moving closer, he was as baffled as he was intrigued. These were museum pieces, as useless to contemporary researchers as mortars and pestles. Oversized bronze microscopes. A polished steel balance. Hand-blown glass condensers with beautiful spiral cooling coils. More prosaic Bunsen burners and ring stands. Over it all lay a thick cover of dust, as if no one had even laid eyes on this magnificent junk in decades.

A skeptic by nature as well as training, Logan nonetheless could not wholly suppress the thought: Was it remotely possible these had once been used by Paul Ehrlich himself?

Now, in the corner, he noticed a stack of wooden crates. Gingerly, he lifted off the top one and set it on the floor. Within were exquisite old bottles that had once contained chemicals, each protectively wrapped in a single sheet of yellowed newspaper. Though their contents had long since vanished, the raised lettering on several indicated what they’d held: concentrated HCl, H₂SO₄, ammonium hydroxide. Other bottles bore glued labels, now brown with age, the spindly handwriting faded almost to invisibility.

Keenly aware that he’d already been down here too long—lunch might already have started—Logan began hastily rewrapping the bottles. But he paused to note the date on the newspaper—7 Juli 1916—and, despite himself, was soon caught up trying to decipher that long-ago day’s events. A terrible battle was in full swing—could it have been the infamous Battle of the Somme?—and the German people were being urged to even greater sacrifices on behalf of their Kaiser and his glorious troops.

Logan picked up another discarded page to look for more. But his eye was quickly drawn to something else: a crumpled sheet of lined notebook paper, wedged in the corner. He picked it up and smoothed out the page. In pencil—difficult to read in the dim light—was the date 25 November 1916, followed by a line of tight script. But what seized his interest was the sketch beneath: twin hexagons sharing a common side and, protruding from the end of each hexagon, additional sulfonate molecules. He took a deep breath, sucking in the musty air. What he held in his hands defied all logic. A primitive version of Compound J!

Carefully, he folded the page, stuck it in his pocket, and resumed putting the bottles back in the crate. Five minutes later, heart racing, he rejoined the group.