Kazuo Ishiguro’s brilliant 2005 novel Never Let Me Go is inherently unfilmable; narrated by a 31-year-old woman who tends to the needs of various organ donors, it thrives on the slowly accumulating tension between the proper British reserve of her prose and the horrible reality lurking beneath the surface of her story. In adapting it to the screen, Alex Garland (Sunshine, 28 Days Later . . .) delivers all the plot highlights, following three children at an exclusive rural boarding school as they grow to adulthood (at which point they’re played by Carey Mulligan, Keira Knightley, and Andrew Garfield). But the theme of Ishiguro’s novel—that we all construct delicate fictions to mask the dehumanization of modern life—proves so elusive onscreen that by the last scene it has to be spelled out in a clumsy, didactic voice-over. The movie is admirable for its resolutely bleak tone, and its three stars, among the cream of young British movie actors, are always worth watching. But for God’s sake, read the book first. Mark Romanek (One Hour Photo) directed; with Charlotte Rampling and Sally Hawkins.