In 'Atonement,' all's unfair in love and war

Given the difficulties in transferring Ian McEwan's trickily structured 2001 novel "Atonement" to the screen, director Joe Wright and screenwriter Christopher Hampton have done a commendable job. Commendable but not electrifying. If one could create a computer program called "Academy Award Winner" – and who's to say someone in Hollywood hasn't already done it? – the results might be something like this.

Set primarily in 1930s and '40s England, it's about the British class caste system and the tragic consequences of a lie. Thirteen-year-old Briony (Saoirse Ronan) is the precocious younger sister of Cecilia (Keira Knightley), who is powerfully drawn to Robbie (James McAvoy), the caretaker's son. Thanks to her well-to-do family, Robbie has attended Cambridge and plans on a medical career. Bewildered and angered by the obvious mutual attraction between these two, Briony commits an unspeakable action that eventually annihilates all three lives.

The first 50 minutes or so leading up to Briony's action are the best. Much as he did in "Pride and Prejudice," Wright delineates an entire society through the microcosm of a single family. McEwan's convoluted time structure is gracefully, almost imperceptibly, rendered.

When the story moves ahead into the outside world and the war with Germany, it loses its focus and becomes more conventional. Knightley, who was at her best in "Pride and Prejudice," is a bit too starchy in the role. Cecilia has large reserves of feeling at her disposal but her lips seem permanently pursed. Perhaps because his character is allowed a greater range of emotion, McAvoy gives a more nuanced and free-wheeling performance. Vanessa Redgrave, as the adult Briony, appears at the very end in a monologue that rounds out the film with heartbreaking force. Grade: B+

• Rated R for disturbing war images, language, and some sexuality.