“Self-sticking,” the tech added with a resigned grimace. Criminalists preferred old-style envelopes that perps had to lick; the adhesive was a good source of DNA. Cooper added that he was familiar with the brand of envelope; it was sold in stores all over the country and virtually untraceable.

Rhyme wheeled closer and, with Dance beside him, watched the tech extract a pocket watch and a note, also the product of a computer printer. “It’s from him,” Cooper announced.

The envelope had been there for no more than a quarter of an hour—the time between Lucy Richter’s departure and Dance’s arrival. Sellitto called Central to have some cars from the nearby Twentieth Precinct sweep the neighborhood. Cooper emailed the Watchmaker’s composite to the house.

The timepiece was ticking and showed the accurate time. It was gold and there were several small dials set in the face.

“Heavy,” Cooper said. He pulled on magnifying goggles and examined it closely. “Looks old, signs of wear . . . no personalized engravings.” He took a camel hair brush and dusted the watch over a piece of newsprint. The envelope too. No trace was dislodged.

“Here’s the note, Lincoln.” He mounted it on an overhead projector.

Dear Mr. Rhyme:

I will be gone by the time you receive this. I have by now, of course, learned that none of the attendees at the conference was injured. I concluded you had anticipated my plans. I then anticipated yours and delayed my trip to Charlotte’s hotel, which gave me the chance to spot your officers. I assume you saved her daughter. I am pleased about that. She deserves better than that pair.

So congratulations. I thought the plan was perfect. But I was apparently wrong.

The pocket watch is a Breguet. It is the favorite of the many timepieces I have come across. It was made in the early 1800s and features a ruby cylinder escapement, perpetual calendar and parachute antishock device. I hope you appreciate the phases-of-the-moon window, in light of our recent adventures. There are few specimens like this watch in the world. I give it to you as a present, out of respect. No one has ever stopped me from finishing a job; you’re as good as they get. (I would say you’re as good as I, but that is not quite true. You did not, after all, catch me.) Keep the Breguet wound (but gently); it will be counting the time until we meet again.

Some advice: If I were you, I would make every one of those seconds count.

—The Watchmaker

Sellitto grimaced.

“What?” Rhyme asked.

“You get classier threats than me, Linc. Usually my perps just say, ‘I’m gonna kill you.’ And what the hell is that?” He pointed to the note. “A semicolon? He’s threatening you and he’s using semicolons. That’s fucked up.”