I parked in the lone spot reserved for visitors. A uniformed security man stopped me just past the front door and asked to see my identification. When I flashed my driver’s license—rather than the CIA badge he had expected—he was instantly on the phone. Waiting for security checks had become a condition of my life; I no longer chafed at it.

Dr. Ginsburg arrived at the desk a few minutes later, accompanied by Tom Rubino. She seemed flustered by the fact that a visitor had actually come to see her. Rubino took over the task of negotiating my passage, and in a few moments I was cleared to go upstairs. Past the entry barrier, the place had the feel of a university lab complex—long corridors lined with shelves, occasional doors bearing prominent biohazard warnings. Ginsburg’s own lab took up most of one wing. In addition to the lab itself she had a large office. Rubino excused himself. He said he had some business to do on the phone but would be back later.

Ginsburg sat me down in her conference room. She reminded me of one of my high school science teachers back in Davis: a woman uncomfortable with her body—you could see it in the way she held her hands awkwardly at her side when she stood—but passionate about the life of the mind. She began her briefing as if it were a college-admission interview.

“What sort of background do you have in biology?” she asked.

“None, to speak of. That’s not my field.”

“I see.” She shook her head sadly. “Mr. Rubino didn’t give me much help in preparing. In fact, he didn’t tell me anything about you at all, except that you will be traveling soon to Beijing and are looking for evidence of French-sponsored biological-weapons research there. I had assumed you were a scientist.”

“No. I’m not a scientist at all. Sorry.” She didn’t seem to have a clue who I was, which was reassuring.

She dimmed the lights and switched on a slide projector, which displayed a color picture of two people in white coats bending over a shallow box containing a clear substance that looked like congealed wax.

“We call this a gel box,” she said. “It’s the first thing you will notice in any serious biotechnology lab. Scientists use it to separate DNA strands, which is the first step in recombinant-DNA engineering. So if you should see one of these boxes, you’ll know they are not making Jell-O.”

“What brand names should I look for on the equipment?”

“French companies. Much of what you’d find in a laboratory in Paris is made by a company called ESI, Équipement Scientifique et Industriel.”

I wrote it down. I wanted to be a good student.