L ike the original, the film version of Ian McEwan's novel Atonement takes place on two vastly different summer days. The first half unfolds in a British manor in 1935. It delves so far into the world of upper classes that I expected Jeeves to wander in. After all, the turning point of the plot is, essentially, a Bertie Wooster-style mistake.

During a heat wave on a weekend, young Robbie (James McAvoy) gets into a scrape. He's the cook's son who is practically a member of the wealthy Tallis family of Wiltshire. Recognizing his talent, the Tallises have sent him to school. Now he's begun to notice young Cecilia Tallis (Keira Knightley), just back from college. They have a small disagreement; a precious vase gets broken. Cecilia strips and dives into the family's fountain to taunt Robbie a little.

Later that day, Robbie writes a small note of apology, which he foolishly gives to Cecilia's prying little sister, 13-year-old Briony (Saoirse Ronan). Worse, he accidentally gives Briony the first draft of the note, composed in midswoon after seeing Cecilia clad only in a wet slip. In a few candid sentences, he describes what he'd like to do to her if he could. This note leads to thorough disaster, implemented by Briony's fervent imagination.

After the calamity, Atonement heads to World War II, where Robbie, now a wounded soldier, atones for his mistake the hard way. The trick in Atonement is that there are other apologies in the offering, and other punishments are handed out by fate. Maybe the worst is life as a nurse in a regimented, pitiless London hospital during the Blitz, a life as bad as that in any prison.

The success of the novel owes partially to the fact that we get it both ways. As in Brideshead Revisited , the twitty, lounging, English-upper-class types show their steel during the war. And yet they also commit unforgivable atrocities against those of us who drop our aitches. The success of the movie is due mostly to the unfussy way director Joe Wright portrays interwar manor life.

Wright is reunited with his star from Pride and Prejudice , the petulant, desirable Keira Knightley. Knightley's body, as slender as any art deco icon, is draped in backless green silk. The color is hard to carry off, but the purpose of it is revealed when heat and desire redden Cecilia's skin, or when the crimson lights from police cars turn her to cinnamon.

Reversing the usual pattern, Wright uses a swift, hand-held camera in the manor and majestically composed scenes for the warfare. The early scenes have the darting camera as Briony deals with a gaggle of unwanted cousins; it's there for the instant that Briony catches Cecilia in mid-coitus, splayed out like a starfish against the library wall.

The real art comes in the later scenes, with Robbie's march to the English Channel with the fleeing British Expeditionary Force. During these scenes, McAvoy advances to the lead rank of English film stars. The revealing shot of the terminal beach at Dunkirk is a stunner. Clammy, smoky light floods in as the camera cranes up. We see the thousands of milling soldiers, junking their trucks and shooting the horses so that the Nazis won't have them. Amid the destruction, the remains of hallucinatory beachfront attractions still stand. A brawl breaks out in a gutted cafe. A choir practices in a gazebo amid the lolling or marching wounded, with a tattered Ferris wheel in the background. The sequence is Atonement's finest moment.

Whether the film transcends the formality of the book is another matter. Atonement starts with a clacking typewriter. It's such a sinister mechanical sound to younger ears, and it becomes the drum track in the title music. This clacking is the emblem of a seriously engrossing but repeatedly overdetermined film. In Atonement , we can't seem to get away from the idea that this is a story, just words on paper.

'Atonement' opens on Friday, Dec. 14, at Rialto Cinemas Lakeside, 551 Summerfield Road, Santa Rosa. 707.525.4840.

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