Spare parts: "Never Let Me Go"

A digest of a modern literary masterpiece. Sort-of sci-fi, in which the clones appear more human than the real thing. An early awards-season pacesetter that ended up with precious little to show for itself. Never Let Me Go really is an odd one, a misfit: you can feel it constantly pushing, striving to get at something profound about lived experience, yet in the end, the tearducts are barely troubled. It's a pretty washout.

Screenwriter Alex Garland has taken the decision to strip Kazuo Ishiguro's novel down to three spare acts: the result gains cinematic shape, but loses a lot of the detail. The opening fast-forward through the Hailsham School years gives only a brief flavour of the environment the three leads - caring Kathy, her sporadically bitchy friend Ruth, and Tommy, the dim yet decent lug who comes between them - grew up in. Charlotte Rampling is on animatronic form, overplaying the creepiness, as the school's headmistress; Sally Hawkins is just a bit too liberal-flouncy as the nice drama teacher who reveals the hideous truth to her charges: that they're being raised in seclusion to provide organ donations for the sick.

Of the child actors, Isobel Meikle-Small is the standout as the young Kathy, ensuring not just a physical but an emotional continuity with Carey Mulligan as her older self. Yet the film is in a hurry to get onto the sixth-form/college years, when it can replace these unknowns with the names and faces on the poster. As the teenage Kathy, Ruth and Tommy, the up-and-coming trio of Mulligan, Keira Knightley and Andrew Garfield form a cohesive unit, a love triangle, a gang with their own secrets and histories; it's pleasing, too, that directors have started to explore, rather than merely prostrate themselves before, the gnarly oddness of Knightley's facial contours.

Yet we don't seem to have enough of these characters on screen; individually, they exist as pallid blanks. Garfield's most notable intervention is to make explicit the kids' suggestibility: we see them imitating moves from US sitcoms, and parrot the restaurant orders of their peers, and for a moment, we grasp just how much these three want to be part of the rest of the world, or at least the in-crowd. The director is Mark Romanek, formerly of pop promos, and he crafts a nice moment with Mulligan alone in her dorm room that underlines the importance of pop music - the title derives from a keening soul number - to young adult lives.

Elsewhere, though, the film raised to the surface a question that nagged at me throughout the novel: what this tale is ultimately about, beyond the vaguest sense of innocence lost. Human connectivity, perhaps - in which case, the movie might be understood as a riposte to The Social Network, with the latter's delineation of the distance between us. Yet if Never Let Me Go wants to be about the pain of seeing your playground crush holding hands with somebody else, that isn't enough in itself to support a whole feature; and if it's trying to be about life, death and the whole damn thing, the handling is just too genteel for its own good. As the characters are in limbo, so too the film seems to be: another middling adaptation of a great book.

Ishiguro, with typical eye for detail and texture, drew you into this reality absolutely, and made these characters' resistance to and resigned acceptance of their situation make complete sense; the film, conversely, is so fussy about structure that its emotional content remains in the realm of the speculative - there's a sense of, well, let's try and adapt the book, and see where it gets us. Romanek did nothing if not impose himself on his 2002 debut One Hour Photo; here, he attempts the kind of directorial self-effacement Fincher managed with The Social Network, and the narrative backs away with him.

You could say he's turned in a very British film, in fact - one that doesn't want to kick up a fuss, even about so emotive a subject as the exploitation of the young - yet its timidity seems more limiting than affecting in any way: all the film achieves is to make something pretty and lulling of forced organ donation, to turn the horror implicit in Ishiguro's novel into the stuff of Sunday afternoon matinees rather than the midnight movie. (Even the big plot revelation takes place in a sleepy Eastbourne sitting room.) In awards terms, it's this year's The Road, an honourable attempt to illuminate words and images that somehow resist filming. But something's missing: an internal motor, any sense of a raging against the dying of the light. Characters who lived - briefly, yet vividly - on the page succumb all too meekly to their destinies on screen.

Never Let Me Go opens nationwide tomorrow.