He hooks up with an unlikely guide in the not inconsiderable shape of Nobody (Gary Farmer), an Indian previously kidnapped and educated in England. Nobody is sure that his William Blake is the self-same poet he read as a child and, realising that the man is dying, undertakes to deliver him to his designated resting-place on the wind-tossed seas.

Jim Jarmusch's arresting new picture, shot in black and white "so it didn't look like Bonanza", is a road movie with horses and six-guns. It's hardly likely territory for this most urban of film-makers, but then Dead Man is hardly your most conventional Western. Obliquely funny, episodic and extremely violent; more Hellman than Ford. It's exactly what a Jim Jarmusch Western would look like: long, languorous, elegiac, farcical.

Blake is a holy innocent. He kills, the bounty on his head spirals, but again and again it's just bad luck. The white man's metal resting near his heart has killed him, the film the journey of a dead man "passing through the surface of a mirror". For that Depp is ideal - chaste and incredibly beautiful, he floats through the carnage and mysticism like a spirit.

Farmer is sublime as the half-educated Indian. At home with his ancestry in a way Blake can never fully appreciate, he has also gained a wry, sardonic take on the white world that places him powerfully outside of both. He rationalises his appointment as Blake's spiritual guide in the complex, ironic voice that gives the film its substance.

Everyone else is inevitably reduced to cameo and an impressive, motley crew they are: Crispin Glover reprises his goggle-eyed loon with a monologue; a raddled-looking Robert Mitchum delivers half his lines straight to a stuffed bear; John Hurt as an obdurate office manager; Alfred Molina is a missionary with God and gun; and, best of all, Iggy Pop pops up as a fur-trapper in a frock and bonnet.

The endless forest traversed by the pair is beautiful, bleak and soulless. The film is shot by Wim Wenders' long-time cinematographer Robby Muller and looks marvellous. He has as much of a feel for black and white as colour, and the images he ushers onto film here are exemplary - the forest mundane and mysterious, Machine an industrial end-of-the-line hell-hole torn straight out of The Elephant Man.

As much as anything that happens in front of the camera, it's Muller and composer Neil Young that emerge as its real stars. Like Ry Cooder on Paris, Texas, Young plays spontaneously to the film, hewing roaring industrial chords from his overdriven electric guitar and wheezy old pump-organ. If Dead Man doesn't look like anything else, it certainly doesn't sound like them either. It's a Western for people who - like Jarmusch - don't like Westerns, a thinking man's Dances With Wolves. John Wayne would hate it, and that, surely, is recommendation enough.