The new “Anna Karenina” is as regal, romantic and tragic as ever. The Tolstoy tale of a bored wife and doting mother martyred by her scandalous love for a rakish cavalry officer in Imperial Russia is a perfect period vehicle for Keira Knightley, who always brings a chest-heaving sexuality to such pieces — even the austere understated romances of Jane Austen.

But her reunion with her “Pride & Prejudice” director Joe Wright has been stage-managed by the great playwright and screenwriter Tom Stoppard. And he’s given Tolstoy something no earlier screen version could claim — playfulness.

Stoppard, of “The Real Inspector Hound” and “Rosencrantz & Guildenstern are Dead,” and Wright imagine the whole of Tolstoy’s rich canvas of 1870s Russia as a stage — the many melodramatic characters in his upper-crust soap opera mere players, actors stepping into the spotlight, leaning over the footlights, or ducking backstage where the ugly “real” world of just-freed peasants and poverty live.

A stellar cast waltz through stunning sets, mixed with painted backdrops and model locomotives, some covered with snow from the pre-Soviet winters. It’s an obvious artifice that renders the over-the-top emotions and overly baroque decadence of Russia’s ruling classes, “polite society,” just a tad risible. And it’s a welcome touch.

Anna Karenina (Knightley) is lost the moment she and the preening pretty boy Count Vronsky, played here by Aaron Taylor-Johnson, exchanging his “Kick Ass” costume for fancy military dress.

“Give me back my peace,” she pants as he curls his mustache and simmers over her.

“There can be no peace between us.”

It’s wrong. It’s sinful. And as Anna’s stiff, saintly statesman-husband (Jude Law, spot on) lectures, “Sin has a price You may be sure of that.”

Anna has a sort of Emma Bovary boredom about her knuckle-cracking spouse, from his imperious ways of ordering her to bed to the fancy silver case he keeps his condoms in.

Vronsky forgets he is supposed to be smitten by young Princess Ekaterina (Alicia Vikander), younger sister to Anna’s sister in law. As reckless as he is rakish, he is catnip to Anna. Countess Lydia (Emily Watson) may lecture her than “We must cherish him, for Russia’s sake,” but Anna’s not buying it.

And even though Anna just talked her sister-in-law (Kelly Macdonald, earthy and distraught) into forgiving and taking back Anna’s wayward brother (Matthew Macfadyen, Knightley’s “Pride & Prejudice” co-star), she tumbles into an affair that will be her ruin. Will she be forgiven, taken back and “saved?”

Every “Karenina” is a product of its times, and Wright and Stoppard take pains to “see” the people the nobility do not — the rail worker killed in an early scene, assorted peasant fieldworkers, servants and the like. In trimming the bulky book, Stoppard makes sure to include the alcoholic pre-Revolution revolutionary (David Wilmot), brother to the sensitive rich-man-of-the-people Constantin (Domhnall Gleeson), who is the noble suitor Ekaterina (Kitty) rejects for Vronsky.

Knightley and Johnson, dolled up so that he looks like a younger Jonathan Rhys-Myers here, have a certain chemistry, but the icy parameters of a stale marriage were never more vividly captured than in the Law’s scenes with the title character. Count Karenin has a sort of compassionate severity that Law, who would have made quite the Vronsky himself ten years ago, ably translates.

It’s an over-familiar story, thanks to the many big and small screen versions of it over the years. But this “Karenina,” from its dancers-frozen-in-place waltzes to the pubic whispers that play like shouted indiscretions, reminds us that all the great period romances weren’t written by Ms. Austen, or even written in English.

MPAA Rating: R for some sexuality and violence

Cast: Keira Knightley, Jude Law, Aaron Taylor-Johnson, Kelly MacDonald, Matthew Macfadyen, Domhnall Gleeson, Emily Watson, Shirley Henderson.

Credits: Directed by Joe Wright, scripted by Tom Stoppard, based on the novel by Leo Tolstoy.. A Focus Features release.

Running time: 2:09