IN THE opening shots of Wim Wenders's new film, written by and starring Sam Shepard, the viewer is taken back into territory explored so well in the duo's 1984 masterpiece, Paris, Texas . . . dusty, mythic Americana and its disenfranchised inhabitants.

A cowboy rides a horse off into the distance. Then the camera swings away to reveal a film set, and its crew wondering where their lead actor has gone. Howard Spence (Shepard), a dog-tired western film star, has had enough of the cocaine, Jack Daniels and young women he keeps in his trailer. He is clearly on the verge of a breakdown and makes a bolt for it on his horse. He needs some time awandering.

You can see the elements lining up: a Wim Wenders road movie; a Sam Shepard script; a loner who has gone off the rails; a lugubrious T Bone Burnett soundtrack and moments of casual beauty. But this is no Paris, Texas, and the result is less than the sum of its parts.

Spence, chased by a private detective (Tim Roth), ditches his cowboy regalia and takes the bus to Elko, Nevada, where his ageing mother (Eva Marie Saint) lives. She keeps a scrapbook detailing all his drug and sex horror stories. She also casually informs him he has a child by a woman he once knew in Butte, Montana. He doesn't know this because he hasn't bothered to visit his mother in 30 years.

Spence begins his road journey, and Wenders indulges his penchant for American iconography. The trip is taken in an ancient Packard. Neon hotel signs light up the screen. Twentyfive years ago in Butte, Spence made a film and had a few flings. One of them, with coffee shop waitress Doreen (Jessica Lange . . . Shepard's real-life wife) produced a son.

He is now a tortured musician who doesn't want to meet dad. Meanwhile, a young hippy called Sky (Sarah Polley) follows him around with an urn under her arm. She turns out to be another daughter.

Wenders is again exploring the outsider who wants to reacquaint with life. Shepard gives a great stark performance as a 60-year-old man picking up the pieces. His face is a museum of years of abuse and regret.

Somehow, though, he falls out of the story. It flaps about and never takes flight . . . Spence unsure what to do with himself, the story uncertain where it should go.