“No.” Alex cut the old man off before he got started on what sounded like becoming an enthusiastic talk on the natural history of the British Isles. A four-thousand-year-old tree seemed unlikely, but it could wait. He did his best to rally.

“Okay, maybe. Maybe there are trees that are thousands of years old. I don’t care. That’s trees. That’s different from—”

“Well, take the Greenland shark, then.”

“The what?”

“Greenland shark. Somniosus microcephalus. Ugly-looking brute but quite the fellow. It’s been estimated the oldest one swimming about today is between three hundred and six hundred years old. Just think: it could’ve attended the first performances of Shakespeare’s plays! Well, if it wasn’t a shark. And, you know, there are whales and tortoises around that are easily getting on for two hundred. And, I mean, the Loch Ness Monster, she’s at least—”

“No, but . . .”

“But when you consider all that, Alex, is there not just the smallest part of you starts to think, Well, the principle is there? Life can be sustained in some creatures for several hundred years, so why not in others? Why not in us? Why not longer? That maybe there are things science has yet to learn about aging? That perhaps it’s possible to slow it—maybe stop it?”

His grandfather paused, offering another opening. Alex had nothing except the roaring between his ears.

“Now, the further you go down that line of thought,” the old man went on, “the more dangerous it becomes, if you ask me. But, I guarantee you, there are scientists right this moment spending billions trying to crack the code. Just as there have always been people trying to unlock the secret, in different ways, for thousands of years. Well, my father is one of them. I told you before: eternal life. It’s his obsession. I just didn’t tell you he’d already gone some way toward achieving it.”

The old man fell silent, as though he had explained anything.

Alex sat trying to pull his tattered thoughts together. Rain hit the windscreen in scattered points of light. The wipers ticked back and forth with a steady, comforting chunk-clunk, spreading the light out in brief, shining, vanishing arcs.

“You know,” his grandfather said happily, “I’d been positively dreading telling you about this, Alex. I mean, I would’ve put it off forever. But now I’ve actually done it, it’s not half as bad as I’d feared. It’s a real weight off the shoulders. There’s a lesson there: don’t keep things bottled up.”

Alex barely heard him. He was wondering how much his mind could take before it finally snapped. Maybe it had already happened.

“Right.” He grabbed the first question he could, just trying to keep the conversation moving before his thoughts seized up or ran away screaming. “So . . . you’re immortal.”