A MURKY CAVERN. HOT, BLACK, DAMP.

The three of them moved quickly down the filthy hallway toward the only doorway Sachs could see. A sign said BOILER ROOM. She was behind the ESU officer, who wore full body armor and helmet. The medic was in the rear.

Her right knuckles and shoulder throbbed from the weight of the suitcase. She shifted it to her left hand, nearly dropped it and readjusted her grip. They continued to the door.

There, the SWAT officer pushed inside and swung his machine gun around the dimly lit room. A flashlight was attached to the barrel and it cast a line of pale light in the shreds of steam. Sachs smelled moisture, mold. And another scent, loathsome.

Click. "Amelia?" The staticky burst of Rhyme's voice scared the absolute hell out of her. "Where are you, Amelia?"

With a shaking hand she turned down the volume.

"Inside," she gasped.

"Is she alive?"

Sachs rocked on her feet, staring at the sight. She squinted, not sure at first what she was seeing. Then she understood.

"Oh, no." Whispering. Feeling the nausea.

The sickening boiled-meat smell wafted around her. But that wasn't the worst of it. Neither was the sight of the woman's skin, bright red, almost orange, peeling off in huge scales. The face completely stripped of skin. No, what brought the dread home was the angle of TJ Colfax's body, the impossible twisting of her limbs and torso as she'd tried to get away from the spray of ravaging heat.

He hoped the vic was dead. For his sake...

"Is she alive?" Rhyme repeated.

"No," Sachs whispered. "I don't see how... No."

"Is the room secure?"

Sachs glanced at the officer, who'd heard the transmission and nodded.

"Scene secure."

Rhyme told her, "I want the ESU trooper out then you and the medic go check on her."

Sachs gagged once on the smell and forced herself to control the reflex. She and the medic walked in an oblique path to the pipe. He bent unemotionally forward and felt the woman's neck. He shook his head.

"Amelia?" Rhyme asked.

Her second body in the line of duty. Both in one day.

The medic said, "DCDS."

Sachs nodded, said formally into the mike, "We have a deceased, confirmed dead at the scene."

"Scalded to death?" Rhyme asked.

"Looks like it."

"Tied to the wall?"

"A pipe. Handcuffed, hands behind. Feet tied with clothesline. Duct-tape gag. He opened the steam pipe. She was only a couple of feet from it. God."

Rhyme continued, "Back the medic out the way you came. To the door. Watch where you put your feet."

She did this, staring at the body. How could the skin be so red? Like a boiled crab shell.

"All right, Amelia. You're going to work the scene. Open the suitcase."

She said nothing. Kept staring.

"Amelia, are you at the door?... Amelia?"

"What?" she shouted.

"Are you at the door?"

His voice was so fucking calm. So different from the snide, demanding voice of the man she remembered in the bedroom. Calm... and something else. She didn't know what.

"Yes, I'm at the door. You know, this is crazy."

"Utterly insane," Rhyme agreed, almost cheerfully. "Is the suitcase open?"

She flipped up the lid and glanced inside. Pliers and forceps, a flex mirror on a handle, cotton balls, eyedroppers, pinking sheers, pipettes, spatulas, scalpels...

What is all this?... a Dustbuster, cheesecloth, envelopes, sifting screens, brushes, scissors, plastic and paper bags, metal cans, bottles — 5 percent nitric acid, ninhydrin, silicone, iodide, friction-ridge-printing supplies.

Impossible. Into the mike she said, "I don't think you believed me, detective. I really don't know anything about CS work."

Eyes on the woman's ruined body. Water dripped off her peeled nose. A bit of white — bone — showed through the cheek. And her face was drawn into an anguished grin. Just like the vic that morning.

"I believed you, Amelia," he said dismissively. "Now, the case is open?" He was calm and he sounded... what? Yes, that was the tone. Seductive. He sounds like a lover.

I hate him, she thought. It's wrong to hate a cripple. But I fucking hate him.

"You're in the basement, right?"

"Yessir."

"Listen, you've got to call me Lincoln. We're going to know each other very well by the time this is over."

Which is gonna be about sixty minutes, tops.

"You'll find some rubber bands in the suitcase, if I'm not mistaken."

"I see some."

"Put them around your shoes. Where the ball of your foot is. If there's any confusion as to footprints you'll know which ones are yours."

"Okay, done."

"Take some evidence bags and envelopes. Put a dozen of each in your pocket. Can you use chopsticks?"

"What did you say?"

"You live in the city, right? You ever go to Mott Street? For General Tsao's chicken? Cold noodles with sesame paste?"

Her gorge rose at the talk of food. She refused to glance at the woman dangling in front of her.

"I can use chopsticks," she said icily.

"Look in the suitcase. I'm not sure you'll find them. They kept them there when I was running scenes."

"I don't see any."

"Well, you'll find some pencils. Put those in your pocket. Now you're going to walk a grid. Cover every inch. Are you ready?"

"Yes."

"First tell me what you see."

"One big room. Maybe twenty by thirty. Full of rusted pipes. Cracked concrete floor. Walls're brick. Mold."

"Any boxes? Anything on the floor?"

"No, it's empty. Except for the pipes, oil tanks, the boiler. There's the sand — the shells, a pile of it spilling out of a crack in the wall. And there's some gray stuff too —"

"'Stuff'?" he jumped. "I don't recognize that word. What's 'stuff'?"

A burst of anger tore through her. She calmed and said, "It's the asbestos but not wadded up like this morning. It's in crumbling sheets."

"Good. Now, the first sweep. You're looking for footprints and any staged clues that he's left for us."

"You think he left more?"

"Oh, I'll betcha," Rhyme said. "Put on the goggles and use the PoliLight. Keep it low. Grid the room. Every inch. Get going. You know how to walk a grid?"

"Yes."

"How?"

She bristled. "I don't need to be tested."

"Ah, humor me. How?"

"Back and forth in one direction, then back and forth in the perpendicular direction."

"Each step, no more than one foot in length."

She hadn't known that. "I know," she said.

"Go ahead."

The PoliLight flashed on with an eerie, otherworldly glow. She knew it was something called an ALS — alternative light source — and that it made fingerprints and semen and blood and some shoeprints fluoresce. The brilliant bile-green light made shadows dance and jump and more than once she nearly drew down on a dark form that turned out to be a mere phantom of darkness.

"Amelia?" Rhyme's voice was sharp. She jumped again.

"Yes? What?"

"Do you see any footprints?"

She continued to stare at the floor. "I, uh, no. I see streaks in the dust. Or something." She cringed at the careless word. But Rhyme, unlike Peretti that morning, paid no attention. He said, "So. He swept up afterwards."

She was surprised. "Yeah, that's it! Broom marks. How'd you know?"

Rhyme laughed — a jarring sound to Sachs in this rank tomb — and he said, "He was smart enough to cover his tracks this morning; no reason to stop now. Oh, he's good, this boy is. But we're good too. Keep going."

Sachs bent over, her joints on fire, and began the search. She covered every square foot of the floor. "Nothing here. Nothing at all."

He picked up on the note of finality in her voice. "You've only just started, Amelia. Crime scenes are three-dimensional. Remember that. What you mean is there's nothing on the floor. Now search the walls. Start with the spot farthest away from the steam and cover every inch."

She slowly circled the horrible marionette in the center of the room. She thought of a Maypole game she'd played at some Brooklyn street feast when she was six or seven, as her father proudly took home movies. Circling slowly. It was an empty room and yet there were a thousand different places to search.

Hopeless... Impossible.

But it wasn't. On a ledge, about six feet above the floor, she found the next set of clues. She barked a fast laugh. "Got something here."

"In a cluster?"

"Yes. A big splinter of dark wood."

"Chopsticks."

"What?" she asked.

"The pencils. Use them to pick it up. Is it wet?"

"Everything in here's wet."

"Sure, it would be. The steam. Put it in a paper evidence bag. Plastic keeps the moisture in and in this heat bacteria'll destroy the trace evidence. What else is there?" he asked eagerly.

"It's, I don't know, hairs, I think. Short, trimmed. A little pile of them."

"Loose or attached to skin?"

"Loose."

"There's a role of two-inch tape in the suitcase. 3M. Pick them up with that."

Sachs lifted most of the hairs, placed them in a paper envelope. She studied the ledge around the hairs. "I see some stains. Looks like rust or blood." She thought to hit the spot with the PoliLight. "They're fluorescing."

"Can you do a presumptive blood test?"

"No."

"Let's just assume it's blood. Could it be the victim's?"

"Doesn't seem to be. It's too far away and there's no trail to her body."

"Does it lead anywhere?"

"Looks like it. To a brick in the wall. It's loose. No prints on it. I'm going to move it aside. I — oh, Jesus!" Sachs gasped and stumbled back a foot or two, nearly fell.

"What?" Rhyme asked.

She eased forward, staring in disbelief.

"Amelia. Talk to me."

"It's a bone. A bloody bone."

"Human?"

"I don't know," she answered. "How would I...? I don't know."

"Recent kill?"

"Looks like it. About two inches long and two in diameter. There's blood and flesh on it. It's been sawn off. Jesus. Who the fuck'd do something —"

"Don't get rattled."

"What if he got it from another victim?"

"Then we better find 'im pretty damn soon, Amelia. Bag it. Plastic for the bone."

As she did this, he asked, "Any other staged clues?" He sounded concerned.

"No."

"That's all? Hairs, a bone and a splinter of wood. He's not making it very easy, is he?"

"Should I bring it back to your... office?"

Rhyme was laughing. "He'd like us to call it quits. But no. We're not through yet. Let's find out a little more about Unsub 823."

"But there's nothing here."

"Oh, yes there is, Amelia. There's his address and his phone number and his description and his hopes and aspirations. They're all around you."

She was furious at his professor's tone and remained silent.

"You have the flashlight?"

"I've got my issue halogen —"

"No," he grumbled. "Issue lights are too narrow. You need the twelve-volt broad beam."

"Well, I didn't bring it," she snapped. "Should I go back and get it?"

"No time. Check out the pipes."

She searched for ten minutes, climbing up to the ceiling, and with the powerful light she illuminated spots that perhaps hadn't been lit in fifty years. "No, I don't see a thing."

"Go back to the door. Hurry."

She hesitated and returned.

"Okay, I'm here."

"Now. Close your eyes. What do you smell?"

"Smell? Did you say smell?" Was he crazy?

"Always smell the air at a crime scene. It can tell you a hundred things."

She kept her eyes wide and breathed in. She said, "Well, I don't know what I smell."

"That's not an acceptable answer."

She exhaled in exasperation and hoped the hiss was coming through his telephone loud and clear. She jammed her lids closed, inhaled, fought the nausea again. "Mold, mustiness. The smell of hot water from the steam."

"You don't know where it's from. Just describe it."

"Hot water. The woman's perfume."

"Are you sure it's hers?"

"Well, no."

"Are you wearing any?"

"No."

"How 'bout aftershave? The medic? The ESU officer?"

"I don't think so. No."

"Describe it."

"Dry. Like gin."

"Take a guess, man's aftershave or woman's perfume."

What had Nick worn? Arrid Extra Dry.

"I don't know," she said. "Man's."

"Walk to the body."

She glanced once at the pipe then down to the floor.

"I —"

"Do it," Lincoln Rhyme said.

She did. The peeling skin was like black-and-red birch.

"Smell her neck."

"It's all... I mean, there isn't much skin left."

"I'm sorry, Amelia, but you have to do it. We have to see if it's her perfume."

She did, inhaled. Gagged, nearly vomited.

I'm going to puke, she thought. Just like Nick and me that night at Pancho's, done in by those damn frozen daiquiris. Two hard-ass cops, swigging down sissy drinks with blue plastic swordfish swimming in them.

"Do you smell the perfume?"

Here it comes... Gagging again.

No. No! She closed her eyes, concentrated on her aching joints. The most painful one — her knee. And, miraculously, the wave of nausea passed. "It's not her perfume."

"Good. So maybe our boy's vain enough to wear a lot of aftershave. That could be a social-class indicator. Or maybe he wants to cover up some other smell he might've left. Garlic, cigars, fish, Whisky. We'll have to see. Now, Amelia, listen carefully."

"What?"

"I want you to be him."

Oh. Psychoshit. Just what I need.

"I really don't think we have time for this."

"There's never enough time in crime scene work," Rhyme continued soothingly. "But that doesn't stop us. Just get into his head. You've been thinking the way we think. I want you to think the way he does."

"Well, how do I do that?"

"Use your imagination. That's why God gave us one. Now, you're him. You've got her cuffed and gagged. You take her into the room there. You cuff her to the pipe. You scare her. You're enjoying this."

"How do you know he's enjoying it?"

"You're enjoying it. Not him. How do I know? Because nobody goes to this much trouble to do something they don't enjoy. Now, you know your way around. You've been here before."

"Why d'you think that?"

"You had to check it out earlier — to find a deserted place with a feeder pipe from the steam system. And to get the clues he left by the train tracks."

Sachs was mesmerized by his fluid, low voice. She forgot completely that his body was destroyed. "Oh. Right."

"You take the steam-pipe cover off. What are you thinking?"

"I don't know. That I want to get it over with. Get out."

But the words were hardly out of her mouth before she thought: Wrong. And she wasn't surprised when she heard Rhyme's tongue click in her headset. "Do you really?" he asked.

"No. I want to make it last."

"Yes! I think that's exactly what you want. You're thinking about what the steam will do to her. What else do you feel?"

"I..."

A thought formed in her mind, vague. She saw the woman struggling to free herself. Saw something else... some one else. Him, she thought. Unsub 823. But what about him? She was close to understanding. What... what? But suddenly the thought vanished. Gone.

"I don't know," she whispered.

"Do you feel any urgency? Or are you pretty cool about what you're doing?"

"I'm in a hurry. I have to leave. The cops could be here at any minute. But I still..."

"What?"

"Shhhh," she ordered, and scanned the room again, looking for whatever had put the seed of the vanished thought in her mind.

The room was swimming, a black, starry night. Swirls of darkness and distant, jaundiced lights. Lord, don't let me faint!

Maybe he —

There! That's it. Sachs's eyes were following the steam pipe. She was looking at another access plate in a shadowy alcove of the room. It would have been a better hiding place for the girl — you couldn't see it from the doorway if you were walking past — and the second plate had only four bolts on it, not eight, like the one he chose.

Why not that pipe?

Then she understood.

"He doesn't want... I don't want to leave just yet because I want to keep an eye on her."

"Why do you think that?" he inquired, echoing her own words just moments before.

"There's another pipe I could've chained her to but I picked the one that was in the open."

"So you could see her?"

"I think so."

"Why?"

"Maybe to make sure she can't get away. Maybe to make sure the gag's tight... I don't know."

"Good, Amelia. But what does it mean? How can we use that fact?"

Sachs looked around the room for the place where he'd have the best view of the girl without being seen. It turned out to be a shadowy spot between two large heating-oil tanks.

"Yes!" she said excitedly, looking at the floor. "He was here." Forgetting the role-playing. "He swept up."

She scanned the area with the bile glow of the PoliLight wand.

"No footprints," she said, disappointed. But as she lifted the light to shut it off, a smudge glowed on one of the tanks.

"I've got a print!" she announced.

"A print?"

"You get a better view of the girl if you lean forward and support yourself on a tank. That's what he did, I'm sure. Only, it's weird, Lincoln. It's... deformed. His hand." She shivered looking at the monstrous palm.

"In the suitcase there's an aerosol bottle labeled DFO. It's a fluorescent stain. Spray that on the print, hit the PoliLight and shoot the image with the one-to-one Polaroid."

She told him when she'd finished this and he said, "Now Dust-bust the floor between the tanks. If we're lucky he scratched off a hair or chewed a fingernail."

My habits, Sachs thought. It was one of the things that had finally ruined her modeling career — the bloody nail, the worried eyebrow. She'd tried and tried and tried to stop. Finally gave up, discouraged, bewildered that a tiny habit could change the direction of your life so dramatically.

"Bag the vacuum filter."

"In paper?"

"Yes, paper. Now, the body, Amelia."

"What?"

"Well, you've got to process the body."

Her heart sank. Somebody else, please. Have somebody else do it. She said, "Not until the ME's finished. That's the rule."

"No rules today, Amelia. We're making up our own. The medical examiner'll get her after us."

Sachs approached the woman.

"You know the routine?"

"Yes." She stepped close to the destroyed body.

Then froze. Hands inches from the victim's skin.

I can't do it. She shuddered. Told herself to keep going. But she couldn't; the muscles weren't responding.

"Sachs? You there?"

She couldn't answer.

I can't do this... It was as simple as that. Impossible. I can't.

"Sachs?"

And then she looked into herself and, somehow, saw her father, in uniform, stooping low on the hot, pitted sidewalk of West Forty-second Street, sliding his arm around a scabby drunk to help him home. Then was seeing her Nick as he laughed and drank beer in a Bronx tavern with a hijacker who'd kill him in a second if he knew the young cop was working undercover. The two men in her life, doing what they had to do.

"Amelia?"

These two images bobbed in her thoughts, and why they calmed her, or where that calm came from, she couldn't begin to guess. "I'm here," she said to Lincoln Rhyme and went about her business as she'd been taught. Taking the nail scrapings, combing the hair — pubic and head. Telling Rhyme what she did as she did it.

Ignoring the dull orbs of eyes...

Ignoring the crimson flesh.

Trying to ignore the smell.

"Get her clothing," Rhyme said. "Cut off everything. Put a sheet of newsprint under them first to pick up any trace that falls off."

"Should I check the pockets?"

"No, we'll do that here. Wrap them up in the paper."

Sachs cut the blouse and skirt off, the panties. She reached out for what she thought was the woman's bra, dangling from her chest. It felt curious, disintegrating in her fingers. Then, like a slap she realized what she held and she gave a short scream. It wasn't cloth, it was skin.

"Amelia? Are you all right?"

"Yes!" she gasped. "I'm fine."

"Describe the restraints."

"Duct tape for the gag, --two inches wide. Standard-issue cuffs for hands, clothesline for the feet."

"PoliLight her body. He might've touched her with his bare hands. Look for prints."

She did. "Nothing."

"Okay. Now cut the clothesline — but not through the knot. Bag it. In plastic."

Sachs did. Then Rhyme said, "We need the cuffs."

"Okay. I've got a cuff key."

"No, Amelia. Don't open them."

"What?"

"The cuff lock mechanism is one of the best ways to pick up trace from the perp."

"Well, how'm I supposed to get them off without a key?" She laughed.

"There's a razor saw in the suitcase."

"You want me to cut off the cuffs?"

There was a pause. Rhyme said, "No, not the cuffs, Amelia."

"Well, what do you want me to... Oh, you can't be serious. Her hands?"

"You have to." He was irritated at her reluctance.

Okay, that's it. Sellitto and Polling've picked a nutcase for a partner. Maybe their careers're tanking but I'm not going down with them.

"Forget it."

"Amelia, it's just another way to collect evidence."

Why did he sound so reasonable? She thought desperately for excuses. "They'll get blood all over them if I cut —"

"Her heart's not beating. Besides," he added like a TV chef, "the blood'll be cooked into a solid."

The gorge rising again.

"Go on, Amelia. Go to the suitcase. Get the saw. In the lid." He added a frosty, "Please."

"Why'd you have me scrape under her nails? I could've just brought you back her hands!"

"Amelia, we need the cuffs. We have to open them here and we can't wait for the ME. It has to be done."

She walked back to the doorway. Unsnapped the thongs, lifted the wicked-looking saw from the case. She stared at the woman, frozen in her tortured pose in the center of the vile room.

"Amelia? Amelia?"

Outside, the sky was still clogged with stagnant, yellow air and the buildings nearby were covered with soot like charred bones. But Sachs had never been so glad to be out in the city air as now. The CU suitcase in one hand, the razor saw in the other, the headset dangling dead around her neck. Sachs ignored the huge crowd of cops and spectators staring at her and walked straight toward the station wagon.

As she passed Sellitto she handed him the saw without pausing, practically tossed it to him. "If he wants it done that badly tell him he can damn well walk down here and do it himself."