Sive Tricycle Theatre, London

Sive, a teenage orphan living with her aunt, uncle and grandmother in the unyielding climate of rural Ireland, is desperate to learn the truth about her parents. "All I know about my mother is that she died when I was a baby." Unbeknown to her, she was conceived out of wedlock and her absent father drowned just days after she was born.

Anyone who saw Martin McDonagh's The Cripple of Inishmaan will be experiencing a weird kind of deja vu. That play pivots around an almost identical set of circumstances. This one also opens with a scene between a cantankerous grandmother and her tough daughter-in-law, thus mirroring McDonagh's first hit, The Beauty Queen of Leenane.

Before anyone leaps to the conclusion that John B Keane is clambering aboard McDonagh's "Oirish" bandwagon, there are two crucial facts to consider. First, Keane is Irish through and through as opposed to Camberwell's McDonagh. Secondly, Sive was written in 1959, before McDonagh was born. This engaging tale is the genuine article.

Then, as now, the key concern for poverty-stricken farmers is money. Mike (doughty Vinnie McCabe) comes home having earned an impressive pounds 16 and 10 shillings. This is put into harsh perspective when he learns from his intractable wife Mena (implacable Marion O'Dwyer) that thanks to the local matchmaker, they could make pounds 200 if they agree to marry off their niece. The groom has "grass for 20 cows and fat cattle besides"; only trouble is, he's nearly four times Sive's age. The rest of this everyday story of country folk is taken up with the tussle of their consciences as they try to separate romance from reality.

Keane builds up the cases for and against with a ripe poetic language. "Never, if the sun, moon and stars fall down out of the heavens," is Mike's initially horrified reaction to his wife's fierce urgings. Elsewhere, notably in the contrived structure with its all-too- convenient appearances and absences, the almost homespun tale is, frankly, hokey. But just as you are about to write him off, he builds a scene of high tension around an unread letter sitting centre-stage, its inflammatory contents burning to be read.

That so much of this amusing play works, despite its creakiness, is a tribute to the cast in this Watford Palace Theatre co-production. Director Ben Barnes misses opportunities to investigate and ignite atmospheres between some of the characters, but Simon O'Gorman as the matchmaker fills the stage with energy, beginning with a seemingly benign cunning and building to a captivating, greedy ruthlessness.

Keane knows there are good yarns and much dramatic mileage to be spun out of closed communities. Although he leans towards old-fashioned melodrama, he has one characteristic (in spades) that McDonagh entirely lacks: heart. The final plot twist is affecting rather than merely clever. Instead of soullessly parading his dramatist's skills, his surprise takes you deeper into the world of his characters.

To 17 Jan (0171-328 1000)