“You two shouldn’t really be here,” Froelich said. “So say nothing, stick close to me and walk fast, OK?”

Then she paused a beat. “But come look at something first.”

She led them through another inconspicuous door and around a corner into a vast dark hall that felt the size of a football field.

“The building’s main lobby,” she said. Her voice echoed in the marble emptiness. The light was dim. White stone looked gray in the gloom.

“Here,” she said.

The walls had giant raised panels carved out of marble, reeded at the edges in the classical style. The one they were standing under was engraved at the top: The United States Department Of The Treasury. The inscription ran laterally for eight or nine feet. Underneath it was another inscription: Roll Of Honor. Then starting in the top left corner of the panel was an engraved list of dates and names. Maybe three or four dozen of them. The next-to-last name on the list was J. Reacher, 1997. Last was M. B. Gordon, 1997. Then there was plenty of empty space. Maybe a column and a half.

“That’s Joe,” Froelich said. “Our tribute.”

Reacher looked up at his brother’s name. It was neatly chiseled. Each letter was maybe two inches high and was inlaid with gold leaf. The marble looked cold, and it was veined and flecked like marble everywhere. Then he caught a glimpse in his mind of Joe’s face, maybe twelve years old, maybe at the dinner table or the breakfast table, always a millisecond faster than anyone else to see a joke, always a millisecond slower to start a smile. Then a glimpse of him leaving home, which at that time was a service bungalow somewhere hot, his shirt wet with sweat, his kitbag on his shoulder, heading out to the flight line and a ten-thousand-mile journey to West Point. Then at the graveside at their mother’s funeral, which was the last time he had seen him alive. He’d met Molly Beth Gordon, too. About fifteen seconds before she died. She had been a bright, vivacious blond woman. Not so very different from Froelich herself.

“No, that’s not Joe,” he said. “Or Molly Beth. Those are just names.”

Neagley glanced at him and Froelich said nothing and led them back to the small lobby with the single elevator. They went up three floors to a different world. It was full of narrow corridors and low ceilings and businesslike adaptations. Acoustic tile overhead, halogen light, white linoleum and gray carpet on the floors, offices divided into cubicles with shoulder-high padded fabric panels on adjustable feet. Banks of phones, fax machines, piles of paper, computers everywhere. There was a literal hum of activity built from the whine of hard drives and cooling fans and the muted screech of modems and the soft ringing of phones. Inside the main door was a reception counter with a man in a suit sitting behind it. He had a phone cradled in his shoulder and was writing something on a message log and couldn’t manage more than a puzzled glance and a distracted nod of greeting.

“Duty officer,” Froelich said. “They work a three-shift system around the clock. This desk is always manned.”

“Is this the only way in?” Reacher asked.

“There are fire stairs way in back,” Froelich said. “But don’t get ahead of yourself. See the cameras?”

She pointed to the ceiling. There were miniature surveillance cameras everywhere there needed to be to cover every corridor.

“Take them into account,” she said.

She led them deeper into the complex, turning left and right until they ended up at what must have been the back of the floor. There was a long narrow corridor that opened out into a windowless square space. Against the side wall of the square was a secretarial station with room for one person, with a desk and file cabinets and shelves loaded with three-ring binders and piles of loose memos. There was a portrait of the current President on the wall and a furled Stars and Stripes in a corner. A coatrack next to the flag. Nothing else. Everything was tidy. Nothing was out of place. Behind the secretary’s desk was the fire exit. It was a stout door with an acetate plaque showing a green man running. Above the exit was a surveillance camera. It stared forward like an unblinking glass eye. Opposite the secretarial station was a single blank door. It was closed.

“Stuyvesant’s office,” Froelich said.

She opened the door and led them inside. Flicked a switch and bright halogen light filled the room. It was a reasonably small office. Smaller than the square anteroom outside it. There was a window, with white fabric blinds closed against the night.

“Does the window open?” Neagley asked.

“No,” Froelich said. “And it faces Pennsylvania Avenue, anyway. Some burglar climbs up three floors on a rope, somebody’s going to notice, believe me.”

The office was dominated by a huge desk with a gray composite top. It was completely empty. There was a leather chair pushed exactly square against it.

“Doesn’t he use a phone?” Reacher asked.

“Keeps it in the drawer,” Froelich said. “He likes the desktop clear.”

There were tall cabinets against the wall, faced with the same gray laminate as the desk. There were two visitor chairs made of leather. Apart from that, nothing. It was a serene space. It spoke of a tidy mind.

“OK,” Froelich said. “The mail threat came on the Monday in the week after the election. Then, on the Wednesday evening, Stuyvesant went home about seven-thirty. Left his desk clear. His secretary left a half hour later. Popped her head in the door just before she went, like she always does. She confirms that the desk was clear. And she’d notice, right? If there was a sheet of paper on the desk, it would stand out.”

Reacher nodded. The desktop looked like the foredeck of a battleship made ready for inspection by an admiral. A speck of dust would have stood out.

“Eight o’clock Thursday morning, the secretary comes in again,” Froelich said. “She walks straight to her own desk and starts work. Doesn’t open Stuyvesant’s door at all. Ten after eight, Stuyvesant himself shows up. He’s carrying a briefcase and wearing a raincoat. He takes off the raincoat and hangs it up on the coatrack. His secretary speaks to him and he sets his briefcase upright on her desk and confers with her about something. Then he opens his door and walks into his office. He’s not carrying anything. He’s left his briefcase on the secretary’s desk. About four or five seconds later he comes back out. Calls his secretary in. They both confirm that at that point, the sheet of paper was there on the desk.”

Neagley glanced around the office, at the door, at the desk, at the distance between the door and the desk.

“Is this just their testimony?” she asked. “Or do the surveillance cameras record to videotape?”

“Both,” Froelich said. “All the cameras record to separate tapes. I’ve looked at this one, and everything happens exactly as they describe it, coming and going.”

“So unless they’re in it together, neither of them put the paper there.”

Froelich nodded. “That’s the way I see it.”

“So who did?” Reacher asked. “What else does the tape show?”

“The cleaning crew,” Froelich said.

She led them back to her own office and took three video-cassettes out of her desk drawer. Stepped over to a bank of shelves, where a small Sony television with a built-in VCR nestled between a printer and a fax machine.

“These are copies,” she said. “The originals are locked away. The recorders work on timers, six hours on each tape. Six in the morning until noon, noon until six, six until midnight, midnight until six, and start again.”

She found the remote in a drawer and switched the television on. Put the first tape in the mechanism. It clicked and whirred and a dim picture settled on the screen.

“This is the Wednesday evening,” she said. “Six P.M. onward.”