The man behind the counter thrived in his own steamy microclimate between a chrome-plated coffee machine, a tea-urn the size of a boiler, and a grill on which half a dozen different meals were sizzling. From the empty taxis outside, it seemed most of the customers were cabdrivers on night shift. Conversations thrummed the air. Alex’s grandfather glanced around, then idly stuffed the salt shaker from the table into his coat pocket.

The entire time they had been there, the old man had persisted in burbling about the weather, about an old film, about food, about nothing. Every now and then, though, he fixed Alex with a long, silent, knowing stare. He knew his grandfather was working up to something—but Alex had questions of his own and was determined this was the night he’d finally get some answers. Before they left this place, he would get his grandfather to admit who the tall man really was. He just needed to think how to begin.

“Marvelous,” the old man repeated, taking another bite. “You know, last place I tried getting a simple egg sandwich, fellow tried to put an avocado on it. I mean, planet’s gone mad. Nothing against the avocado, but there’s a time and a place. Mind you, Harry said he’d tried something similar and . . .” He fell silent again, considered the roll in his hand, then placed it alongside the other lying untouched on his plate and pushed the plate away. “Ha. Not as hungry as I thought.”

Alex wasn’t listening. The mention of Harry Morecambe, his grandfather’s oldest friend, had called up a memory from the whirl of a few months before.

Alex had been alone with Harry, and had tried to quiz him about the tall man’s identity. Finally, reluctantly, Harry had shown him an old photograph from his wallet. Alex had seen it only briefly, yet was certain of what he had seen: his grandfather, supposedly pictured over seventy years earlier, but looking only twenty years younger.

It was an impossible riddle. But Harry had been trying to tell him something that Alex hadn’t been able to figure out. He’d become so caught up in his fascination with the tablet that he’d almost forgotten about it. Now it struck him: Harry hadn’t shown him the picture as an answer. He was trying to tell him the question. Harry had shown him the photograph so he would ask his grandfather about it. Harry was giving him the way in.

Alex’s grandfather lifted the metal teapot to refill his mug. His face fell. “Empty. Hang on.”

The old man crossed to the counter and stood chatting with the man in the steam. Street light made spattered jewels of rain on the black window behind him. Alex’s eyes drifted back to the plate on the table, one roll half-eaten, the other untouched. He’d never known his grandfather to leave food unfinished.