Something is wrong in the world of Never Let Me Go. Exactly what that thing is, and how it affects the three friends at the centre of the story, is unspooled with exquisite understatement - rivetingly controlled, and devastatingly sad.
Kathy, Tommy and Ruth (played by Mulligan, Garfield and Knightley respectively, with some excellent child actors filling the roles in the earlier parts of the story) are students at Hailsham boarding school. Although the film is set in the late '70s, the children live a strangely anachronistic life: dressed in old handknits, playing with shabby toys, watching black-and-white musicals for a treat, they seem to exist in a post-war bubble. And, more peculiar still, they have no parents.
An opening caption informs us that a medical breakthrough in 1952 extended the human lifespan to over 100, but what that has to do with Hailsham is only implied at the start. All the same, these mysterious children are quite ordinary. They have friendships and secrets, they suffer from teasing (poor Tommy most of all) and they fall in love - Kathy with Tommy, before Ruth imposes herself to form a quietly agonising triangle. After school, they move on to a fragile version of adult life together, the immediate heartache of their relationships colliding with the ever-more-imminent, unspeakably terrible fate to which they've been born.
None of this would be so affecting if it wasn't done subtly, and the film benefits from three outstanding performances. Knightley makes the potentially unsympathetic Ruth into an object of compassion; Garfield's Tommy is anguished but never overwrought; and as Kathy, Mulligan is the most important part of the film, conveying a tragic blend of desperation and resignation through not much more than the gentle collapse of the sides of her mouth.
Adapted from a novel by a Japanese-born author and directed by an American, Never Let Me Go is extraordinarily English. Partly that's in the combination of mid-20th century ephemera and bleak seaside settings, but it's also down to the genre - a blend of sci-fi set-up (that critical medical advancement) and achingly human drama. This is a story of loss that grips you tightly (and tearfully) from beginning to end.