Cooper was examining it. "Blond hair. One inch long. Natural, not dyed."

Rhyme loved hair as a forensic tool. It could often be used for DNA sampling-if the bulb was attached-and it could reveal a lot about the suspect's appearance, through color and texture and shape. Age and sex could also be reckoned with more or less accuracy. Hair testing was becoming more and more popular as a forensic and an employment tool since hair retained traces of drugs longer than urine or blood. An inch of hair held a two-month history of drug use. In England hair was frequently used to test for alcohol abuse.

"We're not sure it's his," Sellitto pointed out.

"Of course not," Rhyme muttered. "We're not sure of anything at this point."

But Pulaski said, "It's pretty likely, though. I talked to the owner. He makes sure the busboys wipe the table down after every customer. I checked. And nobody'd wiped it after the perp was there, because of the explosion."

"Good, Rookie."

Cooper continued, speaking of the hair, "No natural or artificial curves. It's straight. No evidence of depigmentation, so I'd put him under fifty years old."

"I want a tox-chem analysis. ASAP."

"I'll send it to the lab."

"A commercial lab," Rhyme ordered. "Wave a lot of money at them for fast results."

Sellitto grumbled, "We don't have a lot of money, and we've got our own perfectly good lab in Queens."

"It's not perfectly good if they don't get me the results before our perp kills somebody else, Lon."

"How's Uptown Testing?" Cooper asked.

"Good. Remember, wave money."

"Jesus, the city doesn't revolve around you, Linc."

"It doesn't?" Rhyme asked, with surprise in his eyes that was both feigned and genuine.

WITH THE SEM-EDS-THE scanning electron microscope and energy-dispersive X-ray spectroscope-Mel Cooper analyzed the trace evidence Sachs had collected where the UNSUB had rigged the wire. "I've got some kind of mineral, different from the substrata around the substation."

"What's it made up of?"

"It's about seventy percent feldspar, then quartz, magnetite, mica, calcite and amphiboles. Some anhydrite too. Curious, large percentages of silicon."

Rhyme knew the geology of the New York area well. When mobile, he'd strolled around the city, scooping up samples of dirt and rock and creating databases that could help him match perp and locale. But this combination of minerals was a mystery to him. It certainly wasn't from around here. "We need a geologist." Rhyme thought for a moment and made a call with speed dial.

"Hello?" a man's soft voice answered.

"Arthur," Rhyme said to his cousin, who lived not far away, in New Jersey.

"Hey. How are you?"

Rhyme reflected that it seemed everybody was asking about his health today, though Arthur was just making conversation.

"Good."

"It was nice seeing you and Amelia last week."

Rhyme had recently reconnected with Arthur Rhyme, who'd been like a brother to him and with whom he'd grown up outside Chicago. Though the criminalist was hardly one for weekends in the country, he'd astonished Sachs by suggesting that the two of them take up an invitation to visit Art Rhyme and his wife, Judy, at their small vacation house on the shore. Arthur revealed that he'd actually built a wheelchair ramp to make it accessible. They'd gone out to the place, along with Thom and Pammy and her dog, Jackson, for a couple of days.

Rhyme had enjoyed himself. While the women and canine hiked the beach, he and Arthur had talked science and academia and world events, their opinions growing inarticulate in direct proportion to the consumption of single malt scotch; Arthur, like Rhyme, had a pretty good collection.

"You're on speaker here, Art, with… well, a bunch of cops."

"I've been watching the news. You're running this electricity incident, I'll bet. Terrible. The press is saying it's probably an accident but…" He gave a skeptical laugh.

"No, not accidental at all. We don't know whether it's a disgruntled employee or a terrorist."

"Anything I can do to help?"

Arthur was a scientist too and somewhat more broad-based than Rhyme.

"Actually, yes. I've got a fast question for you. Well, I hope it's fast. We found some trace at the crime scene and it doesn't match any substrata nearby. In fact, it doesn't match any geologic formation in the New York area I'm familiar with."

"I've got a pen. Give me what you found."

Rhyme recited the results of their tests.

Arthur was silent. Rhyme pictured his cousin lost in thought as he gazed at the list he'd jotted, his mind running through possibilities. Finally he asked, "How big are the particles?"

"Mel?"

"Hi, Art, it's Mel Cooper."

"Hi, Mel. Been dancing lately?"

"We won the Long Island tango competition last week. We're going to regionals on Sunday. Unless I'm stuck here, of course."

"Mel?" Rhyme urged.

"Particles? Yes, very small. About point two five millimeters."

"Okay, I'm pretty sure it's tephra."

"What?" Rhyme asked.

Arthur spelled it. "Volcanic matter. The word's Greek for 'ash.' In the air, after it's blown out of the volcano, it's pyroclast-broken rock-but on the ground it's called tephra."

"Indigenous?" Rhyme asked

In an amused voice, Arthur said, "It's indigenous somewhere. But you mean around here? Not anymore. You could find a very minuscule trace amount in the Northeast given a major eruption on the West Coast and strong prevailing winds, but there haven't been any lately. In those proportions I'd say most likely the source was the Pacific Northwest. Maybe Hawaii."

"So however this got to a crime scene it would have been carried there by the perp or somebody."

"That'd be my call."

"Well, thanks. We'll talk to you soon."

"Oh, and Judy said she's going to email Amelia that recipe she wanted."

Rhyme hadn't heard that part of the conversation during the weekend out of town. It must've occurred on one of the beach walks.

Sachs called, "No hurry."

After they disconnected, Rhyme couldn't help but look at her with a raised eyebrow. "You're taking up cooking?"

"Pammy's going to teach me." She shrugged. "How hard can it be? I figure it's just like rebuilding a carburetor, only with perishable parts."

Rhyme gazed at the chart. "Tephra… So maybe our perp's been to Seattle or Portland recently or to Hawaii. I doubt that much trace would travel very well, though. I'm betting he was in or near a museum, school, geologic exhibit of some kind. Do they use volcanic ash in any kind of business? Maybe polishing stones. Like Carborundum."

Cooper said, "This's too varied and irregular to be milled commercially. Too soft too, I'd think."

"Hm. How about jewelry? Do they make jewelry out of lava?"

None of them had ever heard of that, though, and Rhyme concluded that the source had to be an exhibit or display that the perp had attended or that was near where he lived or where a future target was. "Mel, have somebody in Queens start calling-check out any exhibits, traveling or permanent displays in the area that have anything to do with volcanoes or lava. Manhattan first." He gazed at the access door, wrapped in plastic. "Now, let's look at what Amelia went swimming with. Your turn at bat, Rookie. Make us proud."