These waters have flowed in the same cycle for millions, billions of years, mingling, evaporating, separating again--just as life on this planet continually replicates itself, growing and aging and dying, but not before producing the seeds of its replacement. How can something be at once both timeless and constantly changing? I ponder that a lot and I always end up thinking of this river meeting the sea. Down there, nature is a force unto itself, oblivious to good or evil, to human desires or human laws."

Bartlett was doing a riff on some obsession of his own, Stone decided.

Or maybe it was some of the Zen philosophy that went along with acquiring a world-cla.s.s collection of samurai swords (if you believed the published profiles).

All the same, looking down at the sprawling city and the harbor full of ships, it was hard not to feel omnipotent and humble at the same time.

The thing Bartlett seemed to be getting at, though, was that nature could not be told what to do. And he seemed to be on the verge of declaring himself a part of that unbridled natural force, also powerful enough to do whatever he pleased.

Now they were heading up the Hudson, teeming with early bird tourist cruises and small single-masted sailboats. Bartlett paused to take in the view with satisfaction. Finally he continued his monologue.

"I know we've had our differences, but I'm prepared to try to get past that. I want to talk to you about something I always think of when I fly across this river. Time. I call my obsession Time and the River.

Physicists will tell you that time should be thought of as a kind of fourth dimension. Things are always at a certain place in three dimensions, but when you describe the location of a subatomic particle, for example, you also have to say when it was there. To locate it accurately, you need four dimensions. We think of them all as rigid but what if one of them could be made fluid? What if you could alter the character of time?"

In spite of himself, Stone took the bait. "I don't know what this has to do with anything. n.o.body can alter the pace of time." He found himself recalling a snippet of verse by John Donne:

_O how feeble is man's power,

That if good fortune fall,

Cannot add another hour,

Nor a lost hour recall!

_

"Strictly speaking, that's true," Bartlett said gravely, turning away again to stare out the Plexiglas window, down into the morning s.p.a.ce below them. The Hudson was now a giant ribbon of blue heading north into the mist. "But what if we could alter the clocks in our body to make them run slower?" He smiled then pointed off to his left. "All this below us has happened in a couple of hundred years. What will it look like down there in another hundred years? Will we still need these puny machines to fly, or will there be teleportation? Whatever it is, what would you give to be around to see that? To have your own time slow down while the world around you went on?"

Stone was looking out into s.p.a.ce, wondering... not whether Winston Bartlett was an egomaniacal madman but rather how truly mad he really was.

Flying in the helicopter, he felt like Faust being shown the world by Mephistopheles. Except here Satan was his own father, offering him a teasing prospect of what it would be like to live on and on.

It would make a h.e.l.l of a story. The problem was, miracles always came with some kind of terrible price. What was the price this time?

Then he had another thought. Was that what had happened to Kristen? Was she paying the price for some kind of hubris that pushed nature too far? n.o.body had claimed she had any kind of medical condition that necessitated a stem cell intervention. So had she been experimenting with some other procedure? Had Mephistopheles now called in his marker?

He wanted to ask but the vibration and the noise made his brain feel like it was in a blender.

"Do you understand what I'm saying?" Bartlett went on. "Do you want to be part of the most exciting development in the history of medicine?

Well, this is your chance. There is a majestic experiment under way.

But now we know it's not for the fainthearted. The question is, do you want to live life or just write about it?"

"I think it's time I heard the whole story," Stone said finally, forcing out the words. "What's your part in this 'experiment'?"

"I've put everything at risk, but now I'm this close to controlling the clock. So ... are you my son? My flesh and blood? Do you have the b.a.l.l.s to try it too?"

Stone suspected the question was rhetorical. He was already up to his neck in whatever was going on. He just didn't yet know how big a part of it he was. While he'd been sedated overnight, had they started experiments on him?

He knew that some of the buzz about stem cells involved the fantasy that someday they might be used to forestall the aging process.

Responsible researchers all said that they weren't trying to extend life; they were only hoping to make a normal lifetime more livable.

Rejuvenative medicine. Winston Bartlett, however, had just taken stem cell potential to its obvious conclusion; he was talking about doing what others did not dare. Regenerative medicine.

"What would we give to be able to look forward to thousands of mornings like this, ending it all only when we chose?" he declared his hands sweeping over the dense green beneath them. "Time would become something that merely flows endlessly through us, ever renewing. So- called old age would cease to exist, at least for those with the courage to take the necessary risks."

Now they were moving above the pine forests that comprised the outer ring of the Greater New York suburbs, as below them the green wilds of New Jersey, north of the GW Bridge, were sweeping by.

Hmmm, Stone pondered if a man somehow stopped growing older and n.o.body else did, at some point he'd end up being the same "age " as his grandchildren. That caused him to think again about Amy and wonder if Bartlett would ever reconcile himself to her existence... .

A few minutes later, he looked down and saw a wide clearing in the trees and a red-tile roof. They had arrived but from the air, the Dorian Inst.i.tute gave no clue to the momentous research going on inside.

Bartlett said nothing as they began their descent, and in moments they were settling onto the rooftop landing pad. The downdraft from the rotor cleared away a few soggy leaves, which had somehow blown there, and then the j.a.panese pilot cut the power and the sound died away. When Bartlett opened the side door, the first thing Stone noticed was the fresh, forest-scented morning air against his face.

He found himself wondering whether the roar of the engine had disturbed the patients, but that was almost beside the point. The Dorian Inst.i.tute was not, he now realized, merely about using stem cell technology to heal the sick. Bartlett had been letting him know that it was also about an experiment that was much, much more profound.

In the silence that followed, Bartlett stepped onto the pad and lit a thin, filtered cigar. (For somebody who'd just been talking about how long it was possible to live, the act confounded credulity.) He took a deep drag, then tossed it onto the paving and peered back through the opening.

"Are you able to walk yet?"

"I think I can manage," Stone said. He actually wasn't sure at all. The vibrations of the chopper had done serious damage to his sense of equilibrium.

But he did find he could take small steps. As they moved to the stairwell leading down to the third-floor elevator, Bartlett said, "I know you've been here once before. You tried to sneak in. Grant saw you and sent you packing. Well, this time you're here for real. The full experience. We're going to start by taking you down to the lab and checking you in."

The man, Stone suspected, was trying to hide everything that was going on in his mind. He wanted to talk about grandiose themes, but his mind was really somewhere else. Beneath all the braggadocio, there was the smell of deep, abiding fear. Winston Bartlett was in some kind of major denial.

"You know, life has been good to me," Bartlett declared as though thinking out loud. "I've done and seen things most mortals can only dream of. I'm sixty-seven, but I feel as though I've only just begun to live. And that's what I intend to happen." He turned back to Stone.

"Whether I have a son to share this with remains to be seen."

A son? Stone glanced back at the man Bartlett had called

Ken, who was now shutting down the McDonnell Douglas. Maybe he was a surrogate son for Bartlett. He was clearly a lot more than a bodyguard.

He'd been the one who nabbed Kristen and returned her to the reservation. So what did he think of whatever was going on? Or what about Ally's brother, Grant? He'd claimed he was the son Bartlett longed for and had never had.

Winston Bartlett already had a surfeit of sons.

When they walked through the door and into the hallway of the third floor, it was milling with the breakfast crowd, nurses and patients, but no one took any special notice of Winston Bartlett, the man who had made it all possible. Did they even know who he was? Stone wondered.

"We're going downstairs." Bartlett directed him toward the elevator.

"I'm still offering you a choice. You can be part of the biggest medical advance in human history, or you can be just another impediment."

Stone glanced at his watch. The hour was just shy of nine.

Where is Ally? What kind of procedure has she undergone? Is she okay?

He had to find her.

As they headed down, he felt like it was a descent into some pit of no return. Winston Bartlett had not elaborated on what awaited down there.

It was as though he couldn't bring himself to face whatever it really was.

What was the worst-case scenario at this point?