'Anna Karenina' condenses tragedy

YOU HAVE to wonder if those who purport to be shocked by the David Petraeus scandal have ever opened a book.

Anna Karenina, for instance - the story of a military officer who risks his rank and reputation to pursue an affair with a married woman, despite the awful consequences to all involved.

Leo Tolstoy's novel is the subject of a lavish and ambitious new screen treatment from British director Joe Wright ("Pride and Prejudice," "Atonement"), a guy who's never erred on the side of caution.

His conceit here is to present the novel as a stage play inside of a film - he shows life among the 19th century Russian aristocracy as (literally) a theatrical production.

Meanwhile, he uses traditional cinematic language when the story moves out to the countryside, mimicking the way Tolstoy himself drew contrasts between the artifice of urban life and the fundamental values of life on the land.

Even if the approach leaves you scratching your head, Wright's gift for conjuring the sumptuous image and the engaging performance keeps you interested early.

And what a cast. Keira Knightley has the lead as Anna, the apparently happy wife of a principled aristocrat (Jude Law). Her Anna is such a convincing spokeswoman for the benefits of marriage that she's dispatched to persuade her philandering brother (Matthew Macfadyen, amusing) to reconcile with his own devoted wife.

A key scene: Anna shares a train ride with a disgraced older woman (Olivia Williams) who proffers advice about the risks and rewards of adultery. Even if you haven't read the book, you understand what's being implied in Wright's cleverly staged scene: This is Anna's future.

And indeed, in due time Anna fulfills her destiny as literature's most rivetingly defiant adulteress - so committed to the happiness she finds with Prince Vronsky (Aaron Taylor Johnson) that she risks her marriage, her relationship with her son, her social standing.

Wright's "other" movie moves off the stage, out of the city and into the countryside, where a high-minded young man named Levin (Domhnall Gleeson) heads for his family farm when he believes he's lost his one shot at true love (with Alicia Vikander). He eventually finds love and happiness there despite himself, and looms in the movie as a foil to the increasingly self-destructive Anna.

Levin is often downplayed or dismissed in movie adaptations, but he emerges as a very substantial character here, helped by the movie's straightforward, cinematic treatment of his storyline.

Anna's story, still steeped in high-concept frippery, becomes less engaging as it goes, particularly as Wright massively pares it down to bring the movie to a close at a reasonable hour.

The movie's still gorgeous, but Anna's great tragedy, condensed and accelerated and enacted underneath the visible ropes and pullies of the stage, never attains its power.

Blog: philly.com/KeepItReel