He began drafting his interim report for Singleton. In it, he summarized the steps the investigation had taken, the persons interviewed, the background checks on Marsala, the forensic and SOC data, the analysis of the Museum’s security tapes, and the statements of the relevant security guards. He pointed out that the next step, should Singleton decide to authorize it, would be an expansion of the interview process beyond the Osteology Department. It would mean the wholesale interviewing, cross-correlation, and background examination of all the Museum staff who had worked late that evening — in fact, perhaps the entire Museum staff, whether they had worked late or not.

D’Agosta guessed Singleton wouldn’t go for that. The expense in time, manpower, and cost was too high, given the small chance a lead would turn up. No: he would likely assign a reduced force to the case, let it move to the back burner. In time, that force, too, would be reassigned. Such was the way of the cold case.

He finished the report, read it over quickly, transmitted it to Singleton, and then shut down his tablet computer. When he looked up, he saw — with a sudden shock — that Agent Pendergast was seated in the lone chair across from the tiny desk. D’Agosta had neither seen nor heard him come in.

“Jesus!” D’Agosta said, taking a deep breath to recover from the surprise. “You just love creeping up on people, don’t you?”

“I admit to finding it amusing. Most people are about as aware of their surroundings as a sea cucumber.”

“Thanks, I appreciate that. So what brings you here?”

“You, my dear Vincent.”

D’Agosta looked at him intently. He had heard, the day before, about the murder of Pendergast’s son. In retrospect, D’Agosta understood why Pendergast had been so short with him in the Museum’s rotunda.

“Look,” he began a little awkwardly, “I was really sorry to hear about what happened. You know, when I approached you the other day, I didn’t know about your son, I’d just returned from my honeymoon and wasn’t up on departmental business—”

Pendergast raised a hand and D’Agosta fell silent. “If anyone should apologize, it should be me.”

“Forget it.”

“A brief explanation is in order. Then I would deem it appropriate if the subject was not raised again.”

“Shoot.”

Pendergast sat forward in his chair. “Vincent, you know I have a son, Alban. He was deeply sociopathic. I last saw him a year and a half ago, when he disappeared into the Brazilian jungle after perpetrating the Hotel Killings here in New York.”

“I didn’t hear that.”

“Since then, he never surfaced… until his corpse was placed upon my doorstep four nights ago. How this was effected and who did it, I have no idea. A Lieutenant Angler is investigating, and I fear he is inadequate to the task.”

“Know him well. He’s a damned good detective.”

“I have no doubt he is competent — which is why I had an associate with excellent computer skills delete all DNA evidence of the Hotel Killer from the NYPD files. You may recall that you once made an official report that Alban and the Hotel Killer were one and the same. Luckily for me, that report was never taken seriously. Be that as it may, it would not do to have Angler run my son’s DNA against the database and come up with a hit.”

“Jesus Christ, I don’t want to hear any more.”

“In any case, Angler is up against a most unusual killer and will not succeed in finding him. But that is my concern, not yours. Which brings me to why I’m here. When last we spoke, you had a case you wished to solicit my advice on.”

“Sure. But you must have more important things to do—”

“I would be glad of the diversion.”

D’Agosta stared at the FBI agent. He was as gaunt as usual, but he seemed perfectly composed. The ice-chip eyes returned the look, regarding him coolly. Pendergast was the strangest man he’d ever met, and God only knew what was going on below the surface.

“Okay. Great. I warn you, though, it’s a bullshit case.” D’Agosta went over the details of the crime: the discovery of the body; the particulars of the scene; the mass of forensic evidence, none of which seemed germane; the reports of the security guards; the statements of the curators and assistants in the Osteology Department. Pendergast took it all in, utterly motionless save for the occasional blink of his silvery eyes. Then a shadow appeared in the cubicle, and Pendergast’s eyes shifted.

D’Agosta looked over his shoulder, following Pendergast’s gaze, and saw the tall, heavyset form of Morris Frisby, head of the department. When D’Agosta had first interviewed him, he had been surprised to find not the slope-shouldered, nearsighted curator he’d expected, but a man who was powerful and feared by his staff. D’Agosta had felt a little intimidated himself. The man was wearing an expensive pin-striped suit with a red tie, and he spoke with a crisp, upper-class New York accent. At well over six feet in height, he dominated the tiny space. He looked from D’Agosta to Pendergast and back, radiating irritation at the continued presence of the police in his domain.

“You’re still here,” he said. It was a statement rather than a question.

“The case hasn’t been solved,” said D’Agosta.

“Nor is it likely to be. This was a random crime committed by someone from the outside. Marsala was in the wrong place at the wrong time. The murder has nothing to do with the Osteology Department. I understand you’ve been repeatedly interviewing my staff, all of whom have a great deal of work, important work, on their plates. Can I assume that you’ll be finishing up your investigation in short order and allowing my staff to continue their work in peace?”

“Who is this man, Lieutenant?” Pendergast asked mildly.

“I am Dr. Morris Frisby,” he said crisply, turning to Pendergast. He had dark-blue eyes with very large whites, and they focused on a person like klieg lights. “I am the head of the anthropology section.”

“Ah, yes. Promoted after the rather mysterious disappearance of Hugo Menzies, if I’m not mistaken.”

“And who might you be? Another policeman in mufti?”

With a languid motion, Pendergast reached into his pocket, removed his ID and shield, and waved them at Frisby à la distance.

Frisby stared. “And how is it the feds have jurisdiction?”

“I am here merely out of idle curiosity,” said Pendergast breezily.

“A busman’s holiday, I presume. How nice for you. Perhaps you can tell the lieutenant here to wrap up his case and cease his pointless interruptions of my department’s time and taxpayer dollars, not to mention the occupation of our departmental space.”

Pendergast smiled. “My idle curiosity might lead to something more official, if the lieutenant feels his work is being hindered by an officious, small-minded, self-important bureaucrat. Not you, of course. I speak in general terms only.”

Frisby stared at Pendergast, his large face turning an angry red.

“Obstruction of justice is a serious thing, Dr. Frisby. For that reason I’m so glad to hear from the lieutenant how you’ve been extending your full cooperation to him and will continue to do so.”

Frisby remained rigid for a long moment. And then he turned on his heel to leave.

“Oh, and Dr. Frisby?” Pendergast continued, still in his most honeyed tone.

Frisby did not turn around. He merely paused.

“You may continue your cooperation by digging up the name and credentials of the visiting scientist who recently worked with Victor Marsala and giving them to my esteemed colleague here.”

Now Frisby did turn back. His face was almost black with rage. He opened his mouth to speak.

Pendergast beat him to it. “Before you say anything, Doctor, let me ask you a question. Are you familiar with game theory?”

The chief curator did not answer.

“If so, you would be aware that there is a certain subset of games known to mathematicians and economists as zero-sum. Zero-sum games deal with resources that neither increase nor decrease in amount — they only shift from one player to the other. Given your present frame of mind, were you to speak now, I’m afraid you might say something rash. I would feel it incumbent to offer a rejoinder. As a result of this exchange, you would be mortified and humiliated, which — as dictated by the rules of game theory — would increase my influence and status at your expense. So I’d suggest the most prudent course of action would be for you to remain silent and go about securing the information I asked for with all possible haste.”