Sellitto said, “Vehicle… He’s got a Yellow Cab.”

“Right. And under ‘Other’ add that he knows CS – crime scene – procedures.”

“Which,” Sellitto added, “maybe means he’s had his turn in the barrel.”

“How’s that?” Thom asked.

“He might have a record,” the detective explained.

Banks said, “Should we add that he’s armed with a.32 Colt?”

“Fuck yes,” his boss confirmed.

Rhyme contributed, “And he knows FRs…”

“What?” Thom asked.

“Friction ridges – fingerprints. That’s what they are, you know, ridges on our hands and feet to give us traction. And put down that he’s probably working out of a safe house. Good job, Thom. Look at him. He’s a born law enforcer.”

Thom glowered and stepped away from the wall, brushing at his shirt, which had picked up a stringy cobweb from the wall.

“There we go, folks,” Sellitto said. “Our first look at Mr. 823.”

Rhyme turned to Mel Cooper. “Now, the sand. What can we tell about it?”

Cooper lifted the goggles onto his pale forehead. He poured a sample onto a slide and slipped it under the polarized-light ’scope. He adjusted dials.

“Hmm. This is curious. No birefringence.”

Polarizing microscopes show birefringence – the double refraction of crystals and fibers and some other materials. Seashore sand birefringes dramatically.

“So it isn’t sand,” Rhyme muttered. “It’s something ground up… Can you individuate it?”

Individuation… The goal of the criminalist. Most physical evidence can be identified. But even if you know what it is there are usually hundreds or thousands of sources it might have come from. Individuated evidence is something that could have come from only one source or a very limited number of sources. A fingerprint, a DNA profile, a paint chip that fits into a missing spot on the perp’s car like a jigsaw-puzzle piece.

“Maybe,” the tech responded, “if I can figure out what it is.”

“Ground glass?” Rhyme suggested.

Glass is essentially melted sand but the glassmaking process alters the crystalline structure. You don’t get birefringence with ground glass. Cooper examined the sample closely.

“No, I don’t think it’s glass. I don’t know what it is. I wish I had an EDX here.”

A popular crime lab tool was a scanning electron microscope married to an energy-dispersive X-ray unit; it determined what elements were in trace samples found at crime scenes.

“Get him one,” Rhyme ordered Sellitto, then looked around the room. “We need more equipment. I want a vacuum metal fingerprint unit too. And a GC-MS.” A gas Chromatograph broke down substances into their component elements, and mass photospectrometry used light to identify each one of them. These instruments let criminalists test an unknown sample as small as one millionth of a gram and compare it against a database of a hundred thousand known substances, cataloged by identity and name brand.

Sellitto phoned the wish list in to the CSU lab.

“But we can’t wait for the fancy toys, Mel. You’ll have to do it the old-fashioned way. Tell me more about our phony sand.”

“It’s mixed with a little dirt. There’s loam, flecks of quartz, feldspar and mica. But minimal leaf and decomposed-plant fragments. Flecks here of what could be bentonite.”

“Bentonite.” Rhyme was pleased. “That’s a volcanic ash that builders use in slurry when they’re digging foundations in watery areas of the city where the bedrock’s deep. It prevents cave-ins. So we’re looking for a developed area that’s on or near the water, probably south of Thirty-fourth Street. North of that the bedrock’s much closer to the surface and they don’t need slurry.”

Cooper moved the slide. “If I had to guess, I’d say this is mostly calcium. Wait, something fibrous here.”

The knob turned and Rhyme would’ve paid anything to be looking through that eyepiece. Flashed back to all the evenings he’d spent with his face pressed against the gray sponge rubber, watching fibers or flecks of humus or blood cells or metal shavings swim into and out of focus.

“Here’s something else. A larger granule. Three layers. One similar to horn, then two layers of calcium. Slightly different colors. The other one’s translucent.”

“Three layers?” Rhyme spat out angrily. “Hell, it’s a seashell!” He felt furious with himself. He should have thought of that.

“Yep, that’s it.” Cooper was nodding. “Oyster, I think.”

The oyster beds around the city were mostly off the coasts of Long Island and New Jersey. Rhyme had hoped that the unsub would limit the geographic area of the search to Manhattan – where the victim that morning was found. He muttered, “If he’s opening up the whole metro area the search’ll be hopeless.”

Cooper said, “I’m looking at something else. I think it’s lime. But very old. Granular.”

“Concrete maybe?” Rhyme suggested.

“Possibly. Yes.

“I don’t get the shells then,” Cooper added reflectively. “Around New York the oyster beds’re full of vegetation and mud. This is mixed with concrete and there’s virtually no vegetable matter at all.”

Rhyme barked suddenly: “Edges! What are the edges of the shell like, Mel?”

The tech gazed into the eyepiece. “Fractured, not worn. This’s been pulverized by dry pressure. Not eroded by water.”

Rhyme’s eyes slipped over the Randel map, scanning right and left. Focusing on the leaping dog’s rump.

“Got it!” he cried.

In 1913 F. W. Woolworth built the sixty-story structure that still bears his name, terra-cotta-clad, covered with gargoyles and Gothic sculpture. For sixteen years it was the world’s tallest building. Because the bedrock in that part of Manhattan was more than a hundred feet below Broadway, workmen had to dig deep shafts to anchor the building. It wasn’t long after the groundbreaking that workmen discovered the remains of Manhattan industrialist Talbott Soames, who’d been kidnapped in 1906. The man’s body was found buried in a thick bed of what looked like white sand but was really ground oyster shells, a fact the tabloids had a hey-day with, noting the obese tycoon’s obsession with rich food. The shells were so common along the lower eastern tip of Manhattan they’d been used for landfill. They were what had given Pearl Street its name.

“She’s downtown somewhere,” Rhyme announced. “Probably the east side. And maybe near Pearl. She’ll be underground, about five to fifteen feet down. Maybe a construction site, maybe a basement. An old building or tunnel.”

“Cross-check the EPA diagram, Jerry,” Sellitto instructed. “Where they’re doing asbestos cleanup.”

“Along Pearl? Nothing.” The young officer held up the map he and Haumann were working from. “There’re three-dozen cleanup sites – in Midtown, Harlem and the Bronx. But nothing downtown.”

“Asbestos… asbestos…” Rhyme mused again. What was so familiar about it?

It was 2:05 p.m.

“Bo, we’ve got to move. Get your people down there and start a search. All the buildings along Pearl Street. Water Street too.”

“Man,” the cop sighed, “that’s beaucoup buildings.” He started for the door.

Rhyme said to Sellitto, “Lon, you better go too. This’s going to be a photo finish. They’ll need all the searchers they can get. Amelia, I want you down there too.”

“Look, I’ve been thinking -”

“Officer,” Sellitto snapped, “you got your orders.”

A faint glower crossed her beautiful face.

Rhyme said to Cooper, “Mel, you drive over here in a bus?”

“An RRV,” he answered.

The city’s big crime scene buses were large vans – filled with instruments and evidence-collection supplies, better equipped than the entire labs of many small towns. But when Rhyme was running IRD he’d ordered smaller crime scene vehicles – station wagons basically – containing the essential collection-and-analysis equipment. The Rapid Response Vehicles looked placid but Rhyme had bullied Transportation into getting them fitted with turbocharged Police Interceptor engines. They often beat Patrol’s squad cars to the scene; on more than one occasion the first officer was a seasoned crime scene tech. Which is every prosecutor’s dream.