“We have no idea what happens on stage tonight,” Brian Logan declares as he and his Cartoon de Salvo colleagues, Alex Murdoch and Neil Haigh, are about to plunge into the creation of a full-length play from scratch. But first Logan, a ginger-haired stringbean with an impish spirit, solicits potential titles from the audience. How about Banana Republic? Or maybe The Slums of Hope? When someone cheekily suggests The Birthday Party, the temptation to steal a tiny bolt of thunder from the Pinter revival playing upstairs is irresistible.

Pinter's masterpiece is half a century old, whereas Cartoon de Salvo was founded only a decade ago. Yet since then this plucky British company has earned a reputation for consistently playful performances fuelled by fresh ideas. Although improvisation has been used in past productions, Hard Hearted Hannah marks the first time that the Salvos have risked inventing an entirely new show each night.

As last Saturday's alternative Birthday Party demonstrated, these actors are clever interlopers on the potentially shaky creative ground of improvisation. It was not a quick sketch that they threw themselves into, but a 90-minute scenario that slid between soap opera and romantic satire with a few Pinteresque pauses and fewer loose ends.

By necessity the actors essayed multiple parts. Logan was a cripplingly shy Northerner in therapy, Murdoch his stentorian, nouveau riche lush of a mother and Haigh the lugubrious, busking former husband she left behind. (Great bit: Haigh begging latecomers for spare change.)

She was now shacked up in splendour with a “resting”, ie, failed, actor (Haigh again), whose incurably vain film star son Clyde Owen (Logan again) swanned about from franchise film sets (James Bond, Indiana Jones) to foreign starlets' beds. Murdoch was delicious as the pouty French one, while Haigh did his best to convincingly embody a dignified, milk-loving Icelandic beauty.

Silly? Highly, but also instructive. The Salvos adroitly sprinkled specks of emotional truth atop their comic outlandishness, amusing themselves as they flirted with failure without forgetting our needs. As a bonus, at every performance their made-up- on-the-spot mischief is casually punctuated by live musical interludes delivered in the skiffle-like tradition of an American jug band.

Box office: 0871 2211722. To June 7

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