There was no way to retrieve the flier without giving away that he still had it. Alex reluctantly put the rucksack down, and climbed out after his grandfather.

Five minutes’ walking brought them to a stand of thin trees, through which eventually loomed a stone wall around nine feet high. His grandfather boosted him, and Alex sat straddling the top while the old man stretched to hand up his Gladstone.

Alex’s grandfather considered the climb, then stepped back.

“You know, I’m getting too old to be climbing walls. I think I’ll make life easy on myself. Could you toss down the spring-heels, Alex? They’re in the bag.”

Alex dropped them down one after the other. His grandfather fumbled the second, and it fell heavily by his feet. The old man stood staring at his left hand, flexing the fingers. The hand trembled. Alex watched with growing concern. After a moment his grandfather gave it a quick, dismissive shake, then leaned against the wall, deftly strapped the spring-heels over his boots, and leapt to join him.

He landed unsteadily, swayed, then straightened and winked reassuringly. Alex wasn’t buying it. Something was very wrong. He felt it like a jab in his stomach.

They sat among the branches that pressed around the wall, each surveying the landscape that lay on the other side: more trees, a glimpse of grass beyond. Scanning the scene, Alex found himself looking at the back of his grandfather’s head. The old man turned, their eyes locked, and it was as if they came to an unspoken agreement to acknowledge what they both knew: something was wrong.

“Are you okay, Grandad?” Alex asked. “You’re not, are you?”

“Hmmm? Oh, yes, I—” His grandfather started brightly, then stopped and gazed down. “Well,” he said, without lifting his eyes. “Truth is, I have been a little under the weather.” He paused again, considering. Finally, he looked up and smiled.

“Might as well tell you straight,” he said. “Although none of this has been how I imagined it would be when I told you any of it—I had pictured us sitting in a nice room by a roaring fire, with something good to eat. But here we are. So. I told you that I took my father’s potion for a little while, his elixir of eternal life. And then I stopped.

“I was about twenty-one when he first brought it to me. He explained what it was. Some of it, anyway. He told me he wanted me to take it, too, join him, and I was raised never to disobey my father. It sounded exciting, I suppose, this great secret. At first.