“But they didn’t take the journal.”

“No. It was in Tonio’s office at the university.”

The thought came to me buzzing and electric: if I had been searching for the journal and the answer to a hundred-year-old mystery for twenty years, others might be searching for it too. “How long did Antonio have the journal?”

“No more than a few weeks. Though it made an impression. He told me more than once that he was reading the most extraordinary thing—the diary of the man who stole the Mona Lisa!”

“Oh. So you know its contents.”

“Only that much.”

I asked if he had discussed the journal with anyone else, and he seemed insulted.

“No. Why would I?”

“Did Professor Guggliermo?”

“As he planned to publish something, I imagine he would have kept the discovery to himself.”

“Do you know where he got it?”

“I assume a rare-book dealer. Antonio worked with many, mostly in Florence, a few in Paris and Germany.”

“Did he have a list of those dealers, perhaps a receipt for his purchase of the journal?”

“I went through his papers, and I do not remember coming across it, and Tonio was a very orderly man.” He paused as if picturing something. “Though I did not get to his desk until recently. That first week, I could not face it, you understand.”

“Yes, of course. Did he have a phone book or an appointment book?”

“It was the only messy thing Tonio owned. He had it for years and refused to replace it. Come to think of it, I don’t remember seeing that either.”

“What about his cell phone?”

“Tonio despised them and did not own one.”

Quattrocchi’s pace was agonizingly slow. He’d opened his topcoat and was sweating, unlike me, freezing in my leather jacket. The streets kept changing—wide, then narrow, curved, then angular—until we came into a large open square lined with fancy shops and with an ornate old carousel in the center, though it didn’t seem to be working.

“Piazza della Repubblica, once the site of the old Roman Forum,” Quattrocchi said, pointing out the triumphal arch, which we cut under, then ambled along irregular streets, Quattrocchi’s arm looped through mine. Every few minutes, he’d stop to catch his breath, then he’d take my arm again and we’d start down another narrow street of old ochre-colored buildings. Other than an occasional sigh or catching his breath, Quattrocchi had been mostly quiet, when he suddenly stopped and faced me.

“I just remembered something, a call I received from a collector of rare papers. That’s what he called himself, a collector of rare papers. He said he’d heard about the journal from an old friend of Professor Guggliermo’s, though he did not furnish a name, or if he did, it didn’t mean anything to me. He asked if I knew of its whereabouts and offered a reward.”

“What did you say?”

“That I had no idea what he was referring to. I had already carried out Tonio’s request—that I contact you about the journal—and I had no interest in making money from it. Between Tonio’s pension and my salary, I have more than enough.”