Rhyme constantly urged officers under him to remember that one crime always had multiple scenes associated with it. There was, yes, perhaps just one location where the actual offense had occurred. But there're always entrance and exit routes to consider-and those might be two different paths, or more if multiple perps were involved. There could be staging areas. There could be rendezvous locations. And there could be the motel where they got together to gloat and share the loot afterward. And nine times out of ten, it's those scenes-the secondary or tertiary-where the perps forgot to wear gloves and clean up trace. Sometimes they even left their names and addresses lying around.

Through Sachs's microphone Rhyme had heard the comment and said, "Good call, Rookie. Only lose the 'luck.' "

"Yessir."

"And lose the smug grin too. I saw that."

Pulaski's face went still. He'd forgotten Rhyme was using Amelia Sachs for his eyes as well as ears and legs. He turned and walked off to continue his search for the perp's access to the substation.

Returning inside with her tools, Sachs wiped them down with adhesive pads to remove any contaminating trace. She walked up to the circuit breaker, the spot where the attacker's cable was mounted with the bolts. She started to reach for the metal portion of the wire. Involuntarily her gloved hand stopped before she touched it. She stared at the raw metal gleaming under the beam of her helmet light.

"Sachs?" Rhyme's voice startled her.

She didn't answer. Saw in her mind the hole in the pole, the deadly bits of molten steel, the holes in the young victim.

The lines are dead…

But what if she got her hand on the metal and somebody two or three miles away in a comfy little control room decided to make it undead? Hit a switch, not knowing about the search?

And where the fuck are those damn batteries?

"We need the evidence back here," Rhyme said.

"Right." She slipped a nylon cover over the end of her wrench so that any distinctive marks on her tools wouldn't transfer to the nuts or bolts and be confused with marks left by the perp's. She leaned forward and with only a moment of hesitation fitted the wrench onto the first bolt. With some effort she loosened it, working as quickly as she could, expecting to feel a searing burn at any moment, though she supposed with that much voltage she wouldn't feel anything at all as she was electrocuted.

The second fixture was undone a moment later and she pulled the cable free. Coiling it, she wrapped the wire in plastic sheeting. The bolts and nuts went into an evidence bag. She set these outside the substation door for Pulaski or the technicians to collect and returned to continue her search. Looking at the floor, she saw more footsteps that seemed to match what she thought were the UNSUB's.

Cocking her head.

"You're making me dizzy, Sachs."

She asked herself as much as Rhyme, "What was that?"

"You hear something?"

"Yes, can't you?"

"If I could hear it, I wouldn't be asking."

It seemed to be a tapping of some sort. She walked to the center of the substation and looked over the railing into darkness below.

Her imagination?

No, the sound was unmistakable.

"I do hear it," Rhyme said.

"It's coming from downstairs, the basement."

A regular beat. Not like a human sound.

A timed detonator? she wondered. And thought again about a booby trap. The perp was smart. He'd know that a crime scene team would spare no effort to search the substation. He'd want to stop them. She shared these thoughts with Rhyme.

He replied, "But if he'd put together a trap why hadn't he done it near the wire?"

They came to the same conclusion simultaneously but he voiced the thought: "Because there's some greater threat to him in the basement." Rhyme then pointed out, "If the power's off what's making the noise?"

"It doesn't sound like one-second intervals, Rhyme. It might not be a timer." She was gazing over the railing, careful not to touch the metal.

He said, "It's dark, I can't see much."

"I'm going to find out." And then she started down the spiral staircase.

The metal staircase.

Ten feet, fifteen, twenty. Random shafts of light from the halogens hit portions of the walls down here, but only the upper portions. Below that everything was murky, the smoke residue thick. Her breaths were shallow and she struggled not to choke. As she approached the bottom, two full stories below the main floor, it was hard to see anything; the miner's light reflected back into her eyes. Still, it was the only illumination she had; she swung her head, with the light, from side to side, taking in the myriad boxes and machinery and wires and panels covering the walls.

She hesitated, tapped her weapon. And stepped off the bottom of the stairs.

And gasped as a jolt pierced her body.

"Sachs! What?"

Sachs had missed the fact that the floor was covered in two feet of freezing brackish water. She couldn't see it with the smoke.

"Water, Rhyme. I wasn't expecting it. And look." She focused ten feet or so over her head at a pipe that was leaking.

That was the sound. Not a click, but dripping water. The idea of water in an electrical substation was so incongruous-and so dangerous-that it hadn't occurred to her that this could be the source of the noise.

"Because of the blast?"

"No. He drilled a hole, Rhyme. I can see it. Two holes. Water's also flowing down the wall-that's what's filling up the room."

Wasn't water as good an electrical conductor as metal? Sachs wondered.

And she was standing in a pool of it, right next to an array of wires and switches and connections above a sign: Danger: 138,000 volts

Rhyme's voice startled her. "He's flooding the basement to destroy evidence."

"Right."

"Sachs, what's that? I can't see it clearly. That box. The big one. Look to the right… Yes, there. What is it?"

Ah, finally.

"It's the battery, Rhyme. The backup battery."

"Is it charged?"

"They said it was. But I don't…"

She waded closer and looked down. A gauge on the battery showed that it was indeed charged. In fact, to Sachs, it looked like it was overcharged. The needle was past 100 percent. Then she remembered something else the Algonquin workers had said: not to worry because it was sealed with insulated caps.

Except that it wasn't. She knew what battery caps looked like and this unit had none. Two metal terminals, connected to thick cables, were exposed.

"The water's rising. It'll hit the terminals in a few minutes."

"Is there enough current to make one of those arc flashes?"

"I don't know, Rhyme."

"There has to be," he whispered. "He's using an arc to destroy something that'll lead us to him. Something he couldn't take with him or destroy when he was there. Can you shut the water off?"

She looked quickly. "No faucets that I can see… Hold on a minute."

Sachs continued to study the basement. "I don't see what he wants to destroy, though." But then she spotted it: Right behind the battery, about four feet off the ground, was an access door. It wasn't large-about eighteen inches square.

"That's it, Rhyme. That's how he got in."

"Must be a sewer or utility tunnel on the other side. But leave it. Pulaski can trace it from the street. Just get out."

"No, Rhyme, look at it-it's really tight. He'd have to squeeze through. It's got some good trace on it, has to. Fibers, hair, maybe DNA. Why else would he want to destroy it?"

Rhyme was hesitating. He knew she was right about preserving the evidence but didn't want her caught in another arc flash explosion.

She waded closer to the access door. But as she approached, a tiny wake rose from the disturbance of her legs and the waves nearly crested the battery.