Sachs gave a cautious look.

Rhyme then asked, "What do you have, Mel?"

Peering through the eyepiece of a microscope, the tech said, "Nothing helpful for sourcing him."

" 'Sourcing.' Missed that word when I was in verb school," Rhyme said sourly.

"But I've got one thing," Cooper said, ignoring Rhyme's remark and reading the results from the chromatograph."Traces of substances that the database is saying are ginseng and wolfberry."

"Chinese herbs, maybe tea," Rhyme announced. A case several years ago had involved a snakehead, a smuggler of illegal aliens, and much of the investigation had centered around Chinatown. A police officer from mainland China, helping in the case, had taught Rhyme about herbalism, thinking it might help his condition. The substances had no effect, of course, but Rhyme had found the subject potentially helpful in investigations. At the moment he noted the find, but agreed with Cooper that it wasn't much of a lead. There was a time when those substances would have been found only in Asian specialty shops and what Rhyme called "woo-woo stores." Now products like that were in every Rite Aid pharmacy and Food Emporium throughout the city.

"On the board, if you please, Sachs."

As she wrote, he looked over a series of small evidence bags lined up in a row, with her handwriting on the chain-of-custody cards. They were labeled with directions from the compass.

"Ten little Indians," Rhyme said, intrigued. "What do we have there?"

"I got mad, Rhyme. No, I got fucking furious."

"Good. I find anger liberating. Why?"

"Because we can't find him. So I took samples of substrate from where he might've been. I crawled around in some pretty lousy places, Rhyme."

"Hence the smudge." He looked at her forehead.

She caught his eye. "I'll wash it off later." A smile. Seductive, he believed.

He lifted an eyebrow. "Well, get searching. Tell me what you find."

She pulled on gloves and poured the samples into ten examining dishes. Donning magnifying goggles, she began sifting through them, using a sterile probe to search the contents of each bag. Dirt, cigarette butts, the bits of paper, the nuts and bolts, the bits of what seemed to be rodent shit, hairs, scraps of cloth, candy and fast food wrappers, grains of concrete, metal and stone. The epidermis of underground New York.

Rhyme had learned long ago that in searching for evidence at crime scenes, the key was finding patterns. What repeated itself frequently? Objects in that category could be presumptively eliminated. It was the unique items, those that were out of place, that might be relevant. Outliers, statisticians and sociologists called them.

Nearly everything that Sachs had found was repeated in every dish of the samples. But there was only one thing that was in a category of its own: a very tiny band of curved metal, nearly in a circle, about twice the width of a pencil lead. Though there were many other bits of metal-parts of screws and bolts and shavings-nothing resembled this.

It was also clean, suggesting it had been left recently.

"Where was this, Sachs?"

Rising from her hunched-over pose and stretching, she looked at the label on the bag in front of the dish.

"Twenty feet from the shaft, southwest. It's where he would've had a view of all the wiring connections he'd made. It was under a beam."

So Galt would have been crouching. The metal bit could have fallen from his cuff or clothing. He asked Sachs to hold it up for him to examine closely. She put magnifying goggles on him, adjusted them. Then she took tweezers and picked up the bit, holding it close.

"Ah, bluing," he said. "Used on iron. Like on guns. Treated with sodium hydroxide and nitrite. For corrosion resistance. And good tensile properties. It's a spring of some kind. Mel, what's your mechanical parts database like?"

"Not as updated as when you were chief, but it's something."

Rhyme went online, laboriously typing the pass code. He could use voice recognition, but characters like @%$*-which the department had adopted to improve security-were troublesome to interpret vocally.

The NYPD forensic database main screen popped up and Rhyme started in the Miscellaneous Metals-Springs category.

After ten minutes of scrolling through hundreds of samples he announced, "It's a hairspring, I think."

"What's that?" Cooper asked.

Rhyme was grimacing. "I'm afraid it's bad news. If it's his, it means he might be changing his approach to the attacks."

"How?" Sachs wondered aloud.

"They're used in timers… I'd bet he's worried we're getting close to him. And he's going to start using a timed device instead of a remote control. When the next attack happens, he could be in a different borough."

Rhyme had Sachs bag the spring and mark a chain-of-custody card.

"He's smart," Cooper observed. "But he'll slip up. They always do."

They often do, Rhyme corrected silently.

The tech then said, "Got a pretty good print from one of the remote's switches."

Rhyme hoped it was from somebody else, but, no, it was just one of Galt's-he didn't need to be diligent about obscuring his identity now that they'd learned his name.

The phone buzzed and Rhyme blinked to see the country code. He answered at once.

"Commander Luna."

"Captain Rhyme, we have, perhaps, a development."

"Go ahead, please."

"An hour ago there was a false fire alarm in a wing of the building Mr. Watchmaker was observing. On that floor is an office of a company that brokers real estate loans in Latin America. The owner's a colorful fellow. Been under investigation a few times. It made me suspicious. I looked into the background of this man and he's had death threats made before."

"By whom?"

"Clients whose deals turned out to be less lucrative than they would have wanted. He performs some other functions too, which I cannot find out about too easily. And if I cannot find out about them the answer is simple: He's a crook. Which means he has a very large and efficient security staff."

"So he's the sort of target that would require a killer like the Watchmaker."

"Exactly."

"But," Rhyme continued, "I would also keep in mind that the target could be at the exact opposite end of the complex from that office."

"You think the fire alarm was a feint."

"Possibly."

"I'll have Arturo's men consider that too. He's put his best-and most invisible-surveillance people on the case."

"Have you found anything more about the contents of the package that Logan received? The letter I with the blanks? The circuit board, the booklet, the numbers?"

"Nothing but speculation. And, as I think you would too, Captain, I feel speculation is a waste of time."

"True, Commander."

Rhyme thanked the man again and they disconnected. He glanced at the clock. The time was 10 p.m. Thirty-five hours since the attack at the substation. Rhyme was in turmoil. On the one hand, he was aware of the terrible pressure to move forward with a case in which the progress was frustratingly slow. On the other, he was exhausted. More tired than he remembered being in a long time. He needed sleep. But he didn't want to admit it to anyone, even Sachs. He was staring at the silent box of the phone, considering what the Mexican police commander had just told him, when he was aware of sweat dotting his forehead. This infuriated him. He wanted to wipe it before anyone noticed, but of course that was a luxury not available to him. He jerked his head from side to side. Finally the motion dislodged the drop.

But it also caught Sachs's attention. He sensed she was about to ask if he was feeling all right. He didn't want to talk about his condition, since he'd either have to admit that he wasn't, or lie to her. He wheeled abruptly to an evidence whiteboard and studied the script intently. Without seeing the words at all.