"How many?" Rhyme said, shaking his head as he repeated what Sellitto had just told him. "He's planning ten victims?"

"Looks that way."

Sitting on either side of Rhyme in the lab, Kathryn Dance and Sellitto showed him the composite picture of the Watchmaker that the detective had made at the clock store, using EFIT-Electronic Facial Identification Technology, a computerized version of the old Identi-Kit, which reconstructed a suspect's features from witness prompts. The image was of a white man in his late forties or early fifties, with a round face, double chin, thick nose and unusually light blue eyes. The dealer had added that the killer was a little over six feet tall. His body was lean and his hair black and medium length. He wore no jewelry. Hallerstein recalled dark clothes but couldn't remember exactly what he was wearing.

Dance then recounted Hallerstein's story. A man had called the shop a month earlier, asking for a particular kind of clock-not a specific brand but any one that was compact, had a moon-phase feature and a loud tick. "Those were the most important," she said. "The moon and a loud tick."

Presumably so that the victims could hear the sound as they died.

The dealer ordered ten clocks. When they'd arrived the man came in and paid cash. He didn't give his name or where he was from or why he wanted the clocks but he knew a great deal about timepieces. They talked about collectibles, who'd recently bought certain well-known timepieces at auctions and what horologic exhibits were presently in the city.

The Watchmaker wouldn't let Hallerstein help him out to the car with the clocks. He'd made several trips, carrying them himself.

As for evidence at the shop there was very little. Hallerstein didn't do much cash business, so most of the nine hundred dollars and change that the Watchmaker had paid him was still in the till. But the dealer had told Sellitto, "Won't do you much good if you want fingerprints. He wore gloves."

Cooper scanned the money for prints anyway and found only the dealer's, which Sellitto had taken as controls. The serial numbers on the bills weren't registered anywhere. Brushing the cash for trace revealed nothing but dust with no distinguishing characteristics.

They'd tried to determine exactly when the Watchmaker had contacted the dealer and, reviewing the telephone logs, they found the likely calls. But it turned out that they'd been made from pay phones, located in downtown Manhattan.

Nothing else at Hallerstein's was of any help.

A call came in from Vice, reporting that the officers had no luck finding the prostitute Tiffanee, with e or y, in the Wall Street area. The detective said he'd keep on it but since there'd been a murder most of the girls had vanished from the neighborhood.

It was then that Rhyme's eyes settled on one entry on the evidence chart.

Soil with fish protein…

Dragged from vehicle to alley…

He then looked at the crime scene photos again. "Thom!"

"What?" the aide called from the kitchen.

"I need you."

The young man appeared instantly. "What's wrong?"

"Lie down on the floor."

"You want me to do what?"

"Lie down on the floor. And, Mel, drag him over to that table."

"I thought something was wrong," Thom said.

"It is. I need you to lie down on the floor. Now!"

The aide looked at him with an expression of wry disbelief. "You're kidding."

"Now! Hurry."

"Not on this floor."

"I tell you to wear jeans to work. You're the one who insists on overpriced slacks. Put that jacket on-the one on the hook. Then hurry up. On your back."

A sigh. "This is going to cost you big-time." The aide pulled the jacket on and lay down on the floor.

"Wait, get the dog out of there," Rhyme called. Jackson the Havanese had jumped out of his box, apparently thinking it was playtime. Cooper scooped the dog up and handed him to Dance.

"Can we get on with it? No, zip up the jacket. It's supposed to be winter."

"It is winter," Cooper replied. "It's just not winter inside."

Thom zipped the jacket up to the neck and lay back.

"Mel, put some aluminum dust on your fingers and then drag him across the room."

The tech didn't even bother to ask the purpose of the exercise. He dipped his fingers in the dark gray fingerprint powder and stood over Thom.

"How do I drag him?"

"That's what I want to figure out," Rhyme said. He squinted. "What's the most efficient way?" He told Cooper to grab the bottom of the jacket and pull it up over Thom's face and drag him that way, headfirst.

Cooper pulled off his glasses and gripped the jacket.

"Sorry," he muttered to the aide.

"I know, you're just following orders."

Cooper did as Rhyme told him. The tech was breathing heavily from the effort but the aide moved smoothly along the floor. Sellitto watched impassively and Kathryn Dance was trying to keep from smiling.

"That's far enough. Take the jacket off and hold it open for me."

Sitting, Thom disrobed. "Can I get up off the floor now?"

"Yes, yes, yes." Rhyme was staring at the jacket. The aide climbed to his feet and dusted himself off.

"What's this all about?" Sellitto asked.

Rhyme grimaced. "Damnit, the rookie was right and he didn't even know it."

"Pulaski?"

"Yep. He assumed the fish trace was from the Watchmaker. I assumed it was the victim's. But look at the jacket."

Cooper's fingers had left traces of the aluminum fingerprint powder inside the garment, in exactly the places where the soil had been found on Theodore Adams's jacket. The Watchmaker himself had left the substance on the victim when he was dragging him in the alley.

"Stupid," Rhyme repeated. Careless thinking infuriated him-especially his own. "Now, next step. I want to know everything there is to know about fish protein."

Cooper turned back to the computer.

Rhyme then noticed Kathryn Dance glancing at her watch. "Missed your plane?" he asked.

"I've got an hour. Doesn't look good, though. Not with security and Christmas crowds."

"Sorry," the rumpled detective offered.

"If I helped, it was worth it."

Sellitto pulled his phone off his belt. "I'll have a squad car sent round. I can get you to the airport in a half hour. Lights and sirens."

"That'd be great. I might make it." Dance pulled on her coat and started for the door.

"Wait. I've got an offer for you."

Both Sellitto and Dance turned their heads to the man who'd spoken.

Rhyme looked at the California agent. "How'd you like an all-expenses-paid night in beautiful New York City?"

She cocked an eyebrow.

The criminalist continued. "I'm wondering if you could stay for another day."

Sellitto was laughing. "Linc, I don't believe it. You're always complaining that witnesses are useless. Changing your ways?"

Rhyme frowned. "No, Lon. What I complain about is how most people handle witnesses-visceral, gut feel, all that woo-woo crap. Pointless. But Kathryn does it right-she applies a methodology based on repeatable and observable responses to stimuli and draws verifiable conclusions. Obviously it's not as good as friction ridges or reagent A-ten in drug analysis but what she does is…" He looked for a word. "Helpful."

Thom laughed. "That's the best compliment you could get. Helpful."

"No need to fill in, Thom," Rhyme snapped. He turned to Dance. "So? How 'bout it?"

The woman's eyes scanned the evidence board and Rhyme noticed she wasn't focused on the cold notations of the clues, but on the pictures. Particularly the photographs of Theodore Adams's corpse, his frosted eyes staring upward.