Kazimi checked the time on the wall-mounted digital clock. Five-thirty. Soon he would need to recite the Isha, the fifth of the daily prayers offered by practicing Muslims. He always prayed alone in his bedroom upstairs, never in congregation, as was his communal obligation. It was, however, a forgivable offense given his unique situation.

After the Isha and dinner, and possibly a short nap, he would head back to the lab. Completely spent, and feeling almost ill with fatigue, Kazimi ambled up the spiral metal stairs to the lab’s only exit, his head bent, his arms dangling limply at his sides. He was a handsome, brown-skinned man in his late thirties, fit but not muscular, with slender shoulders and a narrow waist. But the stress of his work, coupled with the lack of sunlight and exercise, had aged him. Kazimi wondered if his former colleagues back at Stanford would even recognize him now.

At the top of the stairs, he pressed his forehead against the visor of the dual iris capture scanner. The red light on the wall-mounted keypad turned to green. From his pants pocket, he withdrew a small contraption, a code creator the size of a credit card. He pressed a button on the creator and the LED screen produced a one-time-only five-digit number, which he entered on the keypad. Almost immediately, he heard the titanium rods securing the door disengage. Getting out of the lab was just as tightly controlled as getting in.

Waiting for him on the other side were two men and a woman—three special agents from the FBI. In addition to his guards, the brownstone was secured with window and door alarms, along with motion-activated security cameras placed throughout. Kazimi never grew too close to his security detail. The agents tasked with his protection rotated every three weeks or so to keep them sharp and focused, and every three or four months they were replaced. It had to be dull protecting a man who toiled alone and worked almost continuously when he wasn’t sleeping or praying.

Kazimi had a remarkably facile memory. By the second time he met them, he knew the names of each agent detailed to him. They exchanged pleasantries and truncated conversations, but as far as he knew, none of the men or women knew about the work he was doing in his basement lab. Three guards was a typical number for his security detail. Some days there were two. On days when he went food or clothes shopping there might even be four. But he could not recall ever having been guarded by just a single person.

The agents were expecting him.