Whenever I have problems with a movie adaptation of a beloved book, it's not too long before people tell me the old chestnut: The book was better. When people inevitably say that about Ian McEwan's novel Atonement, I will have to take their word for it, but I will inherently believe them. The story, which progresses over about 70 years in three different sections with different character focuses in each, probably works quite well as a novel. Indeed, the first two acts of this star-crossed love story are completely involving. The first is a self-contained account of an imaginative young girl whose imagination gets the best of an innocent; the second is an unabashedly romantic tale of unrequited love finally fulfilled.

The third, which switches perspective so suddenly as to make us curious exactly whose story this is really supposed to be, just becomes too much. I'm sure it works on the page, but on screen, it gets clunky, especially in the epilogue, which hardly packs the intended emotional punch as a result. Director Joe Wright gave us a fine version of Jane Austen's Pride & Prejudice a couple years ago, but this adaptation of another British romance isn't on par.

The story begins in England in 1935. Thirteen-year-old Briony Tallis (Saoirse Ronan) is writing a play to be performed on the event of her brother's homecoming. The family has arrived at the Tallis estate for the event, but Briony is most concerned whether or not her brother will like her play. She asks her sister Cecilia (Keira Knightley) and her servants' son Robbie (James McAvoy), whom Briony looks at longingly&mash;even though he has eyes for Cecilia. Briony witnesses the two at a fountain, although what at first appears to be a suspicious event turns out to be completely harmless. Briony doesn't see it that way.

Neither does she see the real letter of apology Robbie intended to give Cecilia; she only sees the one where he vulgarly describes where he wants to kiss her. And when Briony catches Cecilia and Robbie in the library together, she is thoroughly convinced that Robbie is a sex maniac. We know what has actually happened, and it's sweet, not shifty. So when Briony witnesses a crime on the estate grounds, her mind immediately shifts to Robbie, and with the help of her testimony, the son of a servant who wanted to become a doctor is taken away by the police.

This first act is a tight piece of storytelling about the way Briony's flights of fancy become the fodder for harmful gossip mongering and a concise look at class structure and the prejudices that arise from it. The second act takes place fours years after, with Robbie serving in the Army in Northern France and Cecilia nursing the wounded. Before Robbie ships out, the two meet and pick up where they left off that fateful night. She catches him up on the family. Briony is now a nurse, too, as a penance for what she did, Cecilia decides.