Dan Gordon’s theatre adaptation of The Rain Man movie not only improves the original, it introduces to the West End a Hollywood heartthrob as charismatic on stage as screen. Yet Josh Hartnett’s riveting performance as Charlie Babbitt rises high above the erotic and the star cannot be written off as theatrical Viagra or even a 100 per cent herbal alternative. Yes, his classic good looks and physique, in the style of a college Jock, will surely drive the libidos of thousands of heterosexual women and gay men into excited top gear. But Hartnett does something more creative than flash his sex-appeal around.

He takes his lead from Gordon, whose stage version, both bleakly comic and emotionally devastating, dispenses with the film’s celebration of a generous, loving America.This Rain Man shapes a critique of an American paternalism that destroys families, fears emotional candour and cannot tolerate deviation from the norm. Hartnett’s businessman- Charlie reeks of aggression and exudes a chronic impersonality, even when with his girlfriend. He betrays the belligerence of someone who is in a bad mood all his life.

When Hartnett’s Charlie finds his estranged father has died and that a brother, about whose existence he never knew, will inherit the family fortune, he resorts to threats and intimidation. Discovering this brother, Adam Godley’s Raymond, is an institutionalised autistic savant, only spurs Charlie to win custody of him and steal the family millions. While Dustin Hoffman’s brilliant Raymond on film was played in a minor key of detached self-absorption, with sudden screams of distress and agitated mutterings that chilled the heart, the versatile Godley renders Raymond as disappointingly gross and grotesque, from lumbering walk to jerky speech.

Inevitably, Terry Johnson’s production, spoiled by inept lighting that shrouds Hartnett in shadow, dispenses with the road-movie format. Yet this Rain Man retains the unusual comic-pathetic mood when Charlie tries to speed the routine-obsessed Raymond across America, and teaches him to dance and avoid hookers. Jonathan Fensom’s design glides from airport to hotel and to the point when Charlie realises that what links him to Raymond is the psychic damage they both suffered. Hartnett’s Charlie is too withdrawn to let slip his feelings but it becomes clear he understands that only by committing his life to Raymond can he save himself from solipsistic rage and materialism.

Closes 20 December. Information: 0844 412 4648