Theatre: MOJO; Royal Court, London

The scene is Soho in the summer of 1958: Sweets and Potts, two small-time heavies, are popping slimming pills upstairs at Ezra's Atlantic Club, excited because they're on the edge of the big time. Behind the door at the back of the set, Ezra is negotiating with Mr Ross - "a legend south of the river" - over the future of his star discovery, Silver Johnny, a 17-year-old rock singer who can make girls soil their pants with excitement; and as Potts says, "anything makes polite young ladies come their cocoa in public is worth taking a look at".

By morning, though, everything's gone horribly wrong: Ezra's dead, his body in the bins at the back of the club, and Sweets, Potts and whipping- boy Skinny, together with Ezra's psychotic son Baby and right-hand man Mickey, are terrified that they might be next. Their plan is to stay in the club until things have cooled down. In the meantime, old resentments and new suspicions flare up, fuelled by too many slimming pills.

It's not hard to trace the influences in Mojo: there's a lot of David Mamet in the characters' mindless, inarticulate flow of words and their occasional jarring bursts of eloquence. There's also a fair bit of Quentin Tarantino in their playground machismo, the way their lives are ruled by cock-up (sent out to rent some guns, Skinny comes back with a single puny Derringer), and in the moments of grotesquely hilarious violence.

Jez Butterworth's debut isn't startling for its originality, then. But it is startling for the confidence and exuberance with which he has taken a mood and a tone of voice so recognisably American and made them into something unmistakably English: Mamet performed by Max Miller, Reservoir Dogs remade as a Carry On.

It's a seductive mixture, seductively acted by a fine cast. Of course, like so many seductions, it leaves you feeling a bit cheap afterwards. There are plenty of holes to pick in the plot (where are the police all this time? What happens to Mr Ross's many friends?); the balance of power within the club is never set up properly, making it hard to keep track of the shifts and reversals. At times the language slips into grating anachronism ("Nice one" or "Brilliant"), and Ian Rickson's direction goes for some cheap laughs - the dialogue is played too much Vic and Bob, not enough Ronnie and Reggie - so that the tension can never build properly.

But Ultz's tacky, glitzy design and Butterworth's cheapjack crooks' argot between them do create a beautifully self-consistent world - one that doesn't bear much relation to the real world, it's true. The lack of contact with reality is part of Butterworth's point, though. These crooks don't even know what time of day it is. Their conversation sometimes touches concrete reality only tangentially: "So I say stop having a chuckle, inky pinky blah blah blah you're gonna get a kidney punched out. Only language they understand." So, you feel a little let down afterwards. But it was certainly fun while it lasted.

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