“Do you remember where you were when you heard that Princess Diana was dead?”

It’s a little bit absurd as a marker of national trauma, and it flusters the American mind, and yet, on its face, the question is the perfect test of memory for any sentient Briton past childhood.

James Purdew, the lost young man at the center of Sam Taylor’s existential, metafictional detective novel, “The Amnesiac” (Penguin Books, 384 pages, $14), can answer that question in detail when a doctor poses it. What he cannot do is locate three years of his life, the memories of which have vanished from his mind but for the persistent hauntings of evanescent dreams. Among the diaries he’s kept since adolescence, those are the missing years: missing not because he didn’t record them, but because, for reasons that elude him, he’s locked those volumes in a safe that only explosives could crack, and he doesn’t have the key.

Just past his 30th birthday, he’s cut himself adrift from the woman with whom he has lived happily, in Amsterdam, for the last five years. She envisioned a lifetime with him, but settled adulthood is a direction in which he doesn’t care to go. When their breakup shakes him from his inertia, he returns to his college town in England, the scene of his mislaid memories, where he intends to ferret out some clues.

That he proceeds, straight-faced, to keep the bits and pieces he turns up in a box labeled “CLUES” is among the endearing elements of this hallucinatory, postmodern collage of obsession, alienation, and the search for self in a solipsistic age. A detective of sorts James may be; Hercule Poirot he is not.

“The Amnesiac” is a young man’s novel in some ways: its subject matter, its echoes of Mr. Taylor’s biography (in, for example, James’s aborted career as an arts journalist), its sense of the passage of time. A mere decade of disuse is long enough for an elegant Victorian home — a house James knew when he was at university, and where he now lives as he renovates it for a mysterious owner– to have fallen into spooky decrepitude.

The book also wears its myriad literary influences on its sleeve, but it does this well, and never more gleefully than when James encounters a familiar-looking drunk at a pub. “Has anyone ever told you that you look like Philip Larkin?” James finally asks the man.

To James’s surprise, the man scowled and said, ‘That wanker.’

‘Did you know him?’ James asked.

‘Know him? That —-ing bastard. I am him.’

‘Philip Larkin is dead,’ said James, though as soon as the words left his mouth he became unsure as to whether this was actually true. He was fairly certain it must be, but the horrific possibility that he had just told a living man that he was dead made him question the accuracy of his assertion.

For a moment the man looked as though he was going to get angry, then he said, ‘Of course he is. He died in 1985.’

‘Yes,’ James said, relieved. ‘That’s what I thought.’

Reality, for James, is a slippery thing; it’s not only his memory that’s unstable but his mental health, which has broken down before. His perception of the world, often clouded by alcohol, is off-balance, and his deliberate isolation means that he has no counterweight in family or friends. The clues he amasses in his confusion and fear seem to lead somewhere, only to escape his grasp, and ours. We sense that James is in danger, but we don’t know quite how or why.

Who is telling us this story is a question almost as tantalizing as what it was that once occupied the void where James’s past should be. The narrator, ever lurking, occasionally emerges from the shadows just long enough to speak in the first person and make us wonder who he is, how he came to be omniscient, and whether he means James any harm. But his is not the only cloaked identity here. Authorship of various texts within the text — as of James’s own life, which seems out of his control — is an uncertainty throughout.

It’s a fairly bleak, claustrophobic tale, and it risks the reader’s weariness, a danger at which Mr. Taylor winks when James peruses a shelf of books from his youth: “Kafka, Melville, Camus, Beckett and Shakespeare” — all of whom echo in “The Amnesiac.”

As far as James was concerned, these so-called antiheroes deserved everything they got. Surely it was obvious that the land surveyor, K, should just have forgotten about trying to reach the castle and gone home? Similarly, Ahab should have given up on trying to catch the white whale and gone home; Meursault should have lied; Vladimir and Estragon should have left Godot a note and gone to the pub; and Hamlet should just have made up his mind.

But Mr. Taylor, it turns out, is more optimistic than most of his literary heroes. He is also a great believer in the power, even the necessity, of storytelling.

How else, after all, are we to remember?