'A rock'n'roll Jesus with a cowboy mouth'

When the playwright Sam Shepard met aspiring rock star Patti Smith in 1971, the result was an intense affair and a play which hasn't seen the light of day for years. Why revive it now, asks Samantha Ellis

Over a few insomniac, hallucinatory nights, so the legend goes, Sam Shepard and Patti Smith wrote a play and called it Cowboy Mouth. It was 1971 and they were in love. They played themselves in the first American production, but after only a few performances, Shepard did a Stephen Fry and disappeared. It has rarely been performed since.

Matt Peover, who is directing a revival of the play at London's BAC with two American actors (Ben Duhl and Natalie Turner-Jones), describes it as "a pretty intense story of a relationship ­ which I imagine is Patti Smith and Sam Shepard, bottled ­ but it's not expressed on the stage as a relationship..." According to Smith, they improvised it live on stage "in a poetic language drawn from the air, the energy of the people and our own devices."

Cavale (Smith's character) wants to turn Slim into "a rock'n'roll Jesus with a cowboy mouth". The model was probably Dylan, who coined the phrase in Sad-Eyed Lady of the Lowlands. In 1975, four years after Cowboy Mouth, Shepard toured with Dylan, recording his impressions of the protean icon in Rolling Thunder Logbook: "Dylan has invented himself," he noted. "The point isn't to figure him out but to take him in." Shepard himself is no stranger to self-fashioning ­ he'd been named Samuel Shepard Rogers VII but called himself Steve to distinguish him from his father. When he hit New York in 1963 ­ aged 20 ­ he changed his name to Sam.

Shepard started out at a Greenwich Village nightclub where he met Ralph Cook, who introduced him to the theatre. In 1964, Cook's Theater Genesis staged Shepard's first play, Cowboys. In 1969 he married his actress girlfriend O-Lan Johnson and their son, Jesse, was born in 1970.

According to Shepard's biographer Ellen Oumano, "Shepard was a family man to the core, but ... he fell under the powerful spell of the wild, brilliant rock poet Patti Smith." Three years younger than Shepard, Smith was passionate about Rimbaud, rock'n'roll and Robert Mapplethorpe, who had briefly shared her room at the Chelsea Hotel. By the time Shepard moved in, she was writing, painting and singing in the run-up to her debut album, Horses, which was released in 1975. In her 1971 poem, "Sam Shepard: 9 Random Years (7+2)", the rugged actor-playwright is an epic hero with "an amplifier for a heart" and "the sliver of moon carved on his fist." This refers to the couple's love rite, in which they were tattooed by a gypsy ­ Smith got a lightning bolt on her knee.

He was inspired by her music (he moonlighted as drummer for a psychedelic blues band, the Holy Modal Rounders); she was the first to call his freewheeling, convulsive chunks of poetry "arias". They wrote Cowboy Mouth sitting across from one another, pushing a typewriter back and forth, "like a battle," said Smith. Some doubt that her input extended beyond the song lyrics, but for Peover, acting and directing is "like plugging into the DNA of the writer" and the rehearsal process has convinced him that "there must be some Patti Smith in this". In February 1971 she debuted as a performance poet at Cook's theatre. On 12 April, Cowboy Mouth premiered at the Traverse Theatre in Edinburgh, and on 29 April, it opened at the American Place Theater, starring Shepard and Smith as themselves. They had rehearsed in Smith's hotel room, and the set was a recreation of its glorious squalor.

It was directed by Robert Glaudini (who was involved with O-Lan Johnson) and produced in a double bill with Shepard's Black Bog Beast Bait, starring Johnson and directed by her old flame Tony Barsha. No wonder Shepard told his biographer Don Shewey, "the thing was too emotionally packed. I suddenly realised I didn't want to exhibit myself like that, playing my life onstage. It was like being in an aquarium." Without telling anyone, he fled New York. Eventually he and Johnson ­ now reconciled ­ escaped to London, where he directed his Geography of a Horse Dreamer at the Royal Court.

In an interview Smith once gave, she felt that Shepard's departure was presaged in the play. "We were saying our own lines ... two big dreamers who came together but were destined to come to a sad end. It was the true story of Sam and I. We knew we couldn't stay together. He was going to go back to his wife and children, and I was gonna go on my way."

'Cowboy Mouth': BAC, London SW11 (020 7223 2223), Tue to 18 Aug