_He had a high forehead and prominent cheekbones, just like in the photo. And just as in his photo, there was a genuine dichotomy between his face, which looked to be early forties and unwrinkled, and his gray eyes, which were much older. That was it. That was what seemed odd. He was different ages.

Underneath his white lab coat he was wearing a black suit and an open- necked blue shirt. Ally noticed that his fingers were long and delicate, like those of a concert pianist, and overall he had a kind of ghostly presence, as though he were more spirit than man. Although he looked exactly as he did in the photograph in the Gerex Corporation brochure, in person there was an added dimension, a kind of raw magnetism about him. It was more than simply a physician's bedside manner, it was the allure of a pied piper. The first thing you wanted to ask him was _How old are you, really?_ Maybe the next thing you'd want to do was ask him to dinner.

What had she expected? Maybe a self-absorbed nerd researcher in wrinkled stained lab attire, anxious to scurry back to his test tubes.

But in person Karl Van de Vliet was debonair and youthful, living proof that his photo wasn't retouched and was recent. He had to be twenty years older than she was, easily, but to look at him you'd guess he was close to the same age. She was dying to ask him about that but she couldn't think of a polite way to raise the subject.

She introduced herself. "We spoke yesterday." Then she introduced her mother and Maria. "Mom and I talked last night about the clinical trials, and she said she's interested. This morning, unfortunately, I'm not sure she remembers what we discussed."

He placed a hand on Nina's shoulder and studied her face as he smiled at her, embracing her with his eyes. "Well, we're going to see what we can do about that aren't we, Mrs. Hampton?"

"I've got a question right up front" Ally said. "Have we already been entered into the National Inst.i.tutes of Health clinical trials?"

He seemed taken aback for a moment, caught off guard, but then he stepped up to the question.

"As a matter of fact I did take the liberty of authorizing the preliminary NIH paperwork for both of you. Of course it doesn't obligate you in any way. The thing is, there's a lot of red tape, so if you do decide to partic.i.p.ate, the sooner we get that part started the better. On the other hand, if you decide not to, we can just terminate everything at this preliminary stage and you won't even be part of the official record."

Well, Ally thought, that undoubtedly explains why Stone saw our names on the NIH Web site. But why did Van de Vliet look so funny when I brought it up?

He focused on Nina. "Mrs. Hampton, I'm Dr. Van de Vliet. You're a pretty lady, and we've had some luck helping other ladies like you."

"Honey, if I had you in my bedroom, then maybe you could help me."

Oh my G.o.d, Ally thought, she's about to go ribald on us. But that's a sign she's coming out of her funk.

But then she had another thought. Maybe Nina sensed he was older than he looked. Like that paranormal perception that told her Grant was involved in something evil. So far, however, that particular perception hadn't panned out (though Grant clearly was up to something).

Maria was mortified. She blushed and made a disapproving animal noise low in her throat and turned her face away, but Van de Vliet simply smiled even more broadly.

"Mrs. Hampton, I don't think you should be talking that way in front of your daughter." He gave her a wink. "What you and I do together is none of these people's business. But I do think we should consider keeping them informed if only a couple of hints."

Ally found herself wanting just to listen to his voice. There was an intelligent warmth about it that reminded her of a kindly professor at Columbia, a truly gifted architect who also could quote Keats and make you cry. You wanted to give yourself to him. My G.o.d, she thought, how am I going to stand up to this man?

"There're some issues you and I need to discuss," he said turning back to Ally. "The first thing I need to do is take a look at Mrs. Hampton's records. But whatever they say, it won't do any harm to run what we call a 'mental state examination' for her, to establish a general baseline of cognitive impairment as of now."

"How long will that take?"

"Actually, Ellen can start in just a few minutes," he said "Of course, we'll need to hear about the usual danger signs everybody knows. Does Mrs. Hampton have recent-memory loss? Does she get confused about places and people? Does she have trouble handling money and paying her bills?"

"The short answer is yes."

All of those things, Ally knew, had accelerated in the last six months.

It was the tragic, recognizable onset of the latter stages of Alzheimer's. Already more than once Maria had said there were times when she didn't think Nina recognized her. More and more she seemed to be confused, unable some days to find her way around the apartment, and she'd started repeating herself. She often had trouble finding the right words, and she was increasingly paranoid and suspicious. Maria, who had worked with other Alzheimer's patients, feared she might begin hallucinating soon, seeing things that weren't there.

Ally turned to her. It felt obscene to talk about her when she was sitting right there with them.

"Mom, sweetie, do you understand what Dr. Van de Vliet is asking? Do you think you have trouble doing everyday things?"

She knew the answer but she was determined that her mother not be treated like a potted plant.

"Ally, you know that half the time I can't remember a blessed thing.

I'm getting crazy as a b.l.o.o.d.y coot."

Then Nina turned and looked Van de Vliet in the eye.

"I don't want to lose my mind, Doctor. I don't want to see the shade closing in. I can't do crosswords anymore. I used to do them all the time. And all the music I used to know. It was my love and now ...

now I can't tell Scriabin from Strauss half the time. It wasn't supposed to happen that way. I thought my mind would go on forever."

"Mrs. Hampton, if you'll let me, what I want to do is try to work on your recollection. I don't know how much I can help you with crosswords, but then I've never been much good at them myself either.

Your memory of music should improve, though. There are no guarantees, but--"

"Then I'm ready to try it, Doctor," she cut in. "You're all that stands between me and losing the only thing I have left, my past" Next came a burst of rationality. "Now, I hate to be a pest but could you explain what exactly it is you're going to do. I want Ally to hear this too and then maybe she can go over it with me later and help me understand it."

He smiled and reached over and stroked her slightly thinning hair. "I'd be happy to try, Mrs. Hampton. It's actually pretty simple."

Then he turned to Ally. "We touched on some of this on the phone. Do you want to hear it again?"

"Yes, I'm still trying to get it all into my simple mind."

"Well," he began, "to go back to the very beginning of my interest in stem cells the focus of our research has been directed toward challenging the notorious Hayflick limit. Back in the 1960s, Professor Leonard Hayflick discovered that when tissue cells are taken from the body and cultured in a laboratory dish, those cells grow and divide about fifty times, give or take, and then they stop. They have reached old age, senescence. The physical basis of the Hayflick limit is a section of DNA known as telomere, which gets shorter each time the cell divides. Eventually the telomeres become so short that all cell division stops. It's like an internal clock telling them the game is over. They've had their innings."

"And you're saying you've found a way to beat the clock, to stop the telomeres from getting shorter?"

"All cells possess a gene known as the telomerase gene, which can restore the telomeres to their youthful length. But in most cells the gene is permanently repressed and inactive. It is only found in egg and sperm cells, and in cancer cells." He gazed away for a moment as though collecting his thoughts. Then he turned back. "However, we've found that by isolating and inserting an active copy of the telomerase enzyme into adult stem cells, which can be found in minute quant.i.ties throughout the body, we can set their clock back to zero. We extract cells, 'immortalize' them with telomerase, and then return them to the body as a youthful infusion."

"And is that what you'd be doing for Mom?"

"There'd be a series of injections, but given what appears to be her level of mental awareness right now, the procedure probably can be accelerated." He patted Nina on the shoulder.

"All right," Ally said "but can you use the same procedure for someone's heart?"

"Well, yes and no," he said. "Did you bring your medical records? I should have a look at them before making any p.r.o.nouncements."

To prepare for this moment, she'd printed off a copy of the medical files she'd scanned into her computer.

"There're a lot of files," she said, opening her bag. "I've got copies of my EKGs over the past eleven years. Dr. Ekelman, my cardiologist, says my condition is getting progressively worse."

She took the folder out of her bag and handed it to him. He flipped through the files with what seemed an absent manner, almost as though he already knew what was in them and was just going through the motions. Then he looked up.

"Well, your physical condition looks pretty good. You clearly exercise.

And I don't see anything here that would suggest a complication. As to how your procedure might differ from your mother's, I guess the main area of concern is simply the scale." He laid her files on the steel table. "Your heart has reached the stage of aortic valve stenosis where cardiac output no longer can keep up proportionately with vigorous exercise. And that has put an even larger strain on an already weakened condition. What we are about to undertake here corresponds to what might almost be considered an aortic valve replacement, though it is done at the cellular level. We call it regenerative medicine. Millions of cells will be involved We'll attempt to reverse the calcification and also to develop new blood vessels that supply the heart muscle."

"You know, this is so risky. I remember that not long ago they tried to use fetal cell injections into the brain for treating Parkinson's disease. And it turned out that the side effects were horrendous. Why should I a.s.sume that this is any safer?"

He looked pained. "I a.s.sure you we don't do anything here that is remotely like that particular, unfortunate procedure."

She stared at the ceiling trying to grasp what he'd just said. "So how risky do you think this is?" she asked finally. "Truth time."

He looked away again and sighed. There was a long silence in which he seemed to be pondering some extremely troubling thoughts. Finally he turned back.