Turning toward Pulaski she said, "Let's get to work." Sachs walked toward the RRV, binding her crimson hair into a bun, to suit up.

Pulaski hesitated and glanced at the hundred dots of cooling metal disks on the sidewalk and lodged against the front of the building, then at the stiff wire hanging from the window. "They did shut the power off in there, didn't they?"

Sachs just motioned him to follow her.

WEARING DRAB, DARK blue Algonquin Consolidated Power worker overalls, a baseball-style cap without logo and safety glasses, the man busied himself at the service panel in the back of the health club in the Chelsea district of Manhattan.

As he did his work-mounting equipment and stripping, connecting and snipping wires, he thought about the attack that morning. The news was all over the incident. One man was killed and several injured this morning when an overload in a power company substation in Manhattan produced a huge spark that jumped from the station to a bus sign pole, narrowly missing an MTA bus.

"It was like, you know, a lightning bolt," one witness, a passenger on the bus, reported. "Just filled the whole sidewalk. It blinded me. And that sound. I can't describe it. It was like this loud growl, then it exploded. I'm afraid to go near anything that's got electricity in it. I'm really freaked out. I mean, anybody who saw that thing is freaked out."

You're not alone, the man thought. People had been conscious of-and awed and frightened by-electricity for more than five thousand years. The word itself came from the Greek for "amber," a reference to the solidified tree resin that the ancients would rub to create static charges. The numbing effects of electricity created by eels and fish in the rivers and off the coasts of Egypt, Greece and Rome were described at length in scientific writings well before the Christian era.

His thoughts turned to water creatures at the moment since, as he worked, he furtively watched five people swimming slow laps in the club's pool. Three women and two men, all of retirement age.

One particular fish he'd come to be fascinated with was the torpedo ray, which gave its name to the weapons fired by submarines. The Latin word torpore-to stiffen or paralyze-was the source of the name. The ray had, in effect, two batteries in its body made up of hundreds of thousands of gelatinous plates. These generated electricity, which a complicated array of nerves transported through its body like wires. The current was used for defense but also offensively, for hunting. Rays would lie in wait and then use a charge to numb their next meal or sometimes kill it outright-larger rays could generate up to two hundred volts and deliver more amps than an electric drill.

Pretty fascinating…

He finished rigging the panel and regarded his job. Like linemen and master electricians all over the world, he felt a certain pride at the neatness. He'd come to feel that working with electricity was more than a trade; it was a science and an art. Closing the door, he walked to the far side of the club-near the men's locker room. And, out of sight, he waited.

Like a torpedo ray.

This neighborhood-the far West Side-was residential; no workers were getting their jogs or swims or squash games in now, early afternoon, though the place would fill up after working hours with hundreds of locals, eager to sweat away the tensions of the day.

But he didn't need a large crowd. Not at the moment. That would come later.

So people would think he was simply another worker and ignore him, he turned his attention to a fire control panel and took the cover off, examining the guts without much interest. Thinking again about electric rays. Those that lived in salt water were wired in parallel circuits and produced lower voltage because seawater was a better conductor than fresh and the jolt didn't need to be so powerful to kill their prey. Electric rays that inhabited rivers and lakes, on the other hand, were wired in series and produced higher voltage to compensate for the lower conductivity of freshwater.

This, to him, was not only fascinating but was relevant at the moment-for this test about the conductivity of water. He wondered if he'd made the calculations right.

He had to wait for only ten minutes before he heard footsteps and saw one of the lap swimmers, a balding man in his sixties, padding by on slippers. He entered the showers.

The man in the overalls snuck a peek at the swimmer, turning the faucet on and stepping under the stream of steaming water, unaware that he was being studied.

Three minutes, five. Lathering, washing…

Growing impatient, because of the risk of detection, gripping the remote control-similar to a large car-key fob-the man in the overalls felt his shoulder muscles stiffening.

Torpore. He laughed silently. And relaxed.

Finally the club member stepped out of the shower and toweled off. He pulled his robe on and then stepped back into the slippers. He walked to the door leading to the locker room and took the handle.

The overalls man pressed two buttons on the remote simultaneously.

The elderly man gave a gasp and froze.

Then stepped back, staring at the handle. Looking at his fingers and quickly touching the handle once more.

Foolish, of course. You're never faster than electricity.

But there was no shock this time and the man was left to consider if maybe it was a burr of sharp metal or maybe even a painful jolt of arthritis in his fingers that he'd felt.

In fact, the trap had contained only a few milliamps of juice. He wasn't here to kill anyone. This was simply an experiment to tell two things: First, would the remote control switchgear he'd created work at this distance, through concrete and steel? It had, fine. And, second, what exactly was the effect of water on conductivity? This was the sort of thing that safety engineers talked and wrote about all the time but that no one had ever quantified in any practical sense-practical, meaning how little juice did one need to stun somebody wearing damp leather footgear into fibrillation and death.

The answer was pretty damn little.

Good.

Freaked me out…

The man in the overalls headed down the stairwell and out the back door.

He thought again about fish and electricity. This time, though, not the creation of juice but the detection of it. Sharks, in particular. They had, literally, a sixth sense: the astonishing ability to perceive the bioelectrical activity within the body of prey miles away, long before they could see it.

He glanced at his watch and supposed the investigation at the substation was well under way. It was unfortunate for whoever was looking into the incident there that human beings didn't have a shark's sixth sense.

Just as it would soon be unfortunate for many other people in the poor city of New York.