The 2005 novel by Japanese-English master-writer Kazuo Ishiguro, which this film adapts, yields the horrifying truth at its heart only slowly.
There are clues carefully left lying about, but the mind rebels at the idea of picking them up. And all the while, a muted, almost affectless,
tone engages our slightly horrified curiosity: we are uneasy about finding out what's going on but we can't tear our eyes away.
The film version does well to capture the timbre of the original. It's certainly not as nuanced - an opening title-card gives too much away, and the story is told in a more linear, less elliptical fashion - but it remains faithful to the spirit, if not the letter, of the book.
A parable with elements of sci-fi (though, perversely, it's set in the recent past), it's the story of Kathy (Carey Mulligan), Ruth (Keira Knightley) and Tommy (Andrew Garfield), played for a third of the movie by child counterparts.
They are students at, and later suspiciously sheltered alumni of, Hailsham, a faintly Dickensian boarding school in the country. Here a stern headmistress (Charlotte Rampling) urges them to watch their health and reminds them that "the students of Hailsham are special", while doing her best to protect them from the truth of what lies ahead.
If their lack of back story were not already a clue - they never mention a life outside Hailsham - a renegade teacher, Miss Lucy (Sally Hawkins), blurts out the salient facts after 20 minutes or so then is not seen again.
But much of the film's effect derives from the fact that even if we
know what's going on, the main characters don't. The novel let us in on
things at the same rate as the characters; the film keeps us one step ahead, and the effect is, if anything, more heartbreaking.
In using its dystopian context as the setting for what would otherwise have been a conventional romantic triangle, the film becomes a haunting meditation on loss and the evaporation of the dreams of youth.
Mark Romanek, a music video veteran who made the Robin Williams' stalker drama One-Hour Photo, shows a remarkable restraint here, letting his actors do the work.
Wisely he hasn't upped the ante and turned this into a horror story. He understands it's a film about the fragility - and durability - of love in a world gone weird.
Abetted by terrific performances, particularly from Mulligan, whose eyes always seem to be holding more than she gives away, and a remarkably focused Knightley, he's made a film of real heart that will stay with you for days.
Cast: Carey Mulligan, Andrew Garfield, Keira Knightley, Charlotte Rampling, Sally Hawkins
Running time: 104 mins
Rating: M (sex scenes)
Verdict: Model adaptation