There was no source of light, but if someone stood back from the doorway, enough flowed in from the guest room to illuminate most of the space. Three of the four walls were constructed of the same packed red clay as the floor. The fourth, to Gabe's left, was some sort of rough-hewn wood panel. That was all there was to it-a way station for slaves, virtually unchanged for over 160 years.

Frustrated, Gabe turned to leave, then turned back to be certain he hadn't left any telltale footprints. The heels of his boots had, in fact, made several gouges in the earthen floor. The rest of the floor had been brushed smooth, possibly with the old broom.

Careful not to track clay back into the small guest room, he pulled his boots off and set them aside. Then he got down on his knees and was smoothing out the defects when he noticed small bits of loose clay around the bases of the legs of the bench leaning against the paneled wall. It appeared as if the bench had been dragged forward and then pushed back again.

He crawled cautiously to the bench and pulled it toward him. It was fixed to the wall, with just enough space at one end to admit his fingers. A stronger pull and an invisible low doorway opened on almost invisible hinges, revealing a tunnel, similar to the room itself, supported every ten yards or so by upright railroad ties and a crossbeam. The tunnel was quite dark but was faintly lit from somewhere in the distance. Electing not to put on his boots, Gabe crossed the small chamber with one step and entered the tunnel with the next.

In total silence, his senses keyed up, he moved through the deep gloom toward the faint glow in the distance. He had traveled perhaps a hundred yards when he began to hear the thrum of machinery. The faint light, he now realized, was coming from beneath a heavy drape of some kind. Cautiously, he eased the drape aside a few inches. Just beyond it, a brushed-steel door, with glass in the upper half, separated him from a gleaming, tiled, brightly lit corridor. Along the corridor on the right-hand side were five doors identical to the one before him. Each was identified by a letter and number painted just above the glass. In addition, there were name plaques in brass just below several of the panes.

Gabe inhaled, held his breath, opened the door, and slipped inside. The steady, mechanical humming was coming from the far end of the corridor. Otherwise, there was neither sound nor movement. He angled himself to be able to see through the glass of the first door, labeled B-10. Below the glass, a bronze plate read: DR. K. RAWDON.

The room, gleaming beneath white fluorescent lights, was clearly a lab of some sort, devoid, at the moment, of people. There were several computer terminals set alongside a complex apparatus that was a tangled arrangement of thick and thin highly polished metal tubes, connected by numerous rivets and bolts and constructed around a series of lenses and eyepieces. The effect was as if he were looking at the inner workings of a nuclear submarine.

But Gabe knew better.

His study of the materials borrowed from Jim Ferendelli's library had disclosed a number of images of equipment nearly identical to the apparatus in Room B-10. The instrument was, he felt certain, a scanning tunneling microscope, capable of mapping the surface of materials atom by atom. It was this instrument, more than any other, that was elemental in the design and construction of nano-scale systems. It had become, in essence, the basis of the entire field of nanotechnology.

CHAPTER 39

Lester, how're you doing?"

Grateful for her hands-off headset, Alison worked the wrapper off a stick of Trident and slipped it into her mouth to join the two sticks already there. From the moment she spotted Treat Griswold heading for his car, she knew this was going to be a three-stick operation. Three at least.

"I'm just passing Dale City," Lester said. "Is he out yet?"

"He's out. Just getting into his car. Lester, listen, are you sure you want to go through with this?"

She already knew the answer. Everything about the man said that the greater the challenge, the more he welcomed it. He was slightly built, with bright dark eyes that suggested he was up to something even when he was just sitting still. After connecting with him by the Lincoln Memorial, Alison had treated him to some coffee from a kiosk and found a bench where they could talk. The deal to move ahead was consummated after just a few minutes.

Lester had told her not to worry about his last name, only the three-hundred-dollar fee they had agreed upon-this after she had offered him five hundred. He was a busker, he said-a street performer with simple tastes. Nothing more, nothing less. Alison strongly sensed there was much more to the man, but he admitted only to being an entertainer, who did contract work from time to time for the FBI to keep his juices flowing.

"Why would I not want to go through with it?" he said now.

Alison waited until two cars had inserted themselves between her and Griswold's Jeep, and then eased into the flow.

"Lester, this is not any normal man. He's built like a small ox, he's trained to kill, and he's armed. I know you're the one who's putting himself in harm's way, but I'm getting cold feet."

"In that case," Lester said, "let's make it three twenty-five."

"Okay, okay, three twenty-five it is. Well, traffic's not bad. We're almost out of the city. As soon as our man passes the exit to his place up here, we'll know he's headed to Fredericksburg. You dressed appropriately?"

"Just like you wanted. Plus a little Jack Daniel's cologne to heighten the effect. I know a good idea when I hear one. This is going to work, Alison. Piece of cake."

"Lester, who are you?"

She could almost see him grinning.

"Like I told you in the park, just someone who needs a little danger and excitement in his life every now and then, and who owes your friend Seth a favor-make that a couple of favors. He said you were the real deal and wouldn't be setting this up if it weren't important. That's all I have to know."

"Your call."

"Now we're talking."

"In that case, I would think Seth's glowing recommendation would qualify me to learn how you did that thing with the Tic Tacs."

"A Congressional Medal of Honor wouldn't qualify you for that one. How's it going with our man?"

"We're coming to the exit he'd be taking to his house up here… and… and… he's driven past it. We're on, my friend."

"Okay. I have the Fredericksburg street map spread out right here. I'm going to find a safe place to leave this jalopy of mine not too far from the garage. Then I'll walk over there and practice looking like I'm picking the lock until he gets there."

"The right-hand door. He's not as likely to take you apart for trying to open that one rather than the one with the Porsche behind it. Just don't get busted by any of the local police. I'll call and let you know when he's getting off of Ninety-five."

"Good enough. But then I'm going to leave my cell phone under the seat. You just relax and have a Tic Tac."

Despite the gum. Alison's mouth seemed dry as she followed the Jeep from three car-lengths behind. Traffic was perfect-not too dense, not too light. As they approached the Dumfries exit, Griswold suddenly broke with the pattern Alison had anticipated he would be following. At the last possible moment, he whipped the Jeep to the right and down the exit ramp. She could almost see him scanning the rearview mirror for any sudden movement from any of the cars behind him. If she duplicated his move, she would be giving herself away. Helpless, she tapped the brake once and continued down the highway as she dialed Lester's number to warn him something was wrong and they should consider backing off and trying another time.