Emma Thompson's greatest successes have involved a keen feeling for English period manners - marked by Oscars for Howards End and The Remains Of The Day (actress) and Sense And Sensibility (adapted screenplay).

She's not a limited talent, at all, but it's these period pieces that have defined her.

Effie Gray marks Thompson's first original screenplay and her first real subject, a spirited young woman who nonetheless suffers an ignominy shocking for even those eccentrically nasty and chauvinist Victorians.

It opens with the tinge of fairy story, as 18-year-old Gray (Dakota Fanning) recounts the meeting of her family and the art critic John Ruskin (Greg Wise), when she was a child in Scotland. Ruskin befriended the girl, appearing kindly and attentive, even writing a book for her; now she's of age, he has married her.

Gray is full of excitement as she moves to London with her new husband. But as soon as we see this man with his coddling parents (Julie Walters and David Suchet, both quite terrifying) we suspect there's too much of the mother's boy about him, and something too irredeemably precious. On their wedding night, Gray discovers this for herself.

It seems there are two Ruskins. As a critic, he is intelligent, sensitive, excited about the new - not least the pre-Raphaelites, whose success is largely due to his support; as a man, he is feeble, cold and cruel. As a critic he champions imperfection, but in life he cannot countenance what he sees as "imperfect" in his wife.

There follows years of loveless and unconsummated marriage, Ruskin's disinterest sucking the lifeblood out of her. The only glimmers of light are offered by Lady Eastlake (Thompson), who's had her own experience of a husband in need of thawing, and the pre-Raphaelite painter John Millais (Tom Sturridge), who unlike his patron is able to marry passion for art with passion for life.

After a hugely successful career as a child actress (War Of The Worlds, Twilight), the American Fanning makes an assured move to maturity, as well as an alien culture and accent. She conveys Gray's courage, confusion and deep pain with touching understatement.

If it seems remiss of Thompson not to reveal what prevented Ruskin from sleeping with a young woman he chose to marry, she's simply being faithful to the mystery of the man himself, who was never very clear on the matter. Greg Wise is a dab hand at rogues (note his dashing cad in Sense And Sensibility) but excels himself here, with a nuanced performance that presents Ruskin as at once monstrous and deeply pathetic, a man so unable to enjoy himself that he declares: "I can't go into company without injury." It's enough to make me regret my student admiration for the critic.

For his part, Sturridge has an innately feral quality that is perfect for the flesh-and-blood presence caught in the middle of the couple; whatever Millais's desires or intentions, he at least reminds Gray that she's a woman.

This is not a bodice-ripping melodrama about adultery, but a restrained account of psychological torture; given the historical facts, it probably couldn't have been otherwise.

As such, it's certainly affecting. And yet I can't help feeling that director Richard Laxton (making his first film, after a long career in television) is sucked too deeply into Ruskin's inertia. I would have liked to have seen more of the pre-Raphaelites' world - to feed some fervour into the mix.