Triptych, Southwark Playhouse, London HH

Triptych, directed by Sean Mathias, shows the effects of a married man's affair on his daughter, mistress, and wife, the man appearing only as a huge pair of eyes glowering at each end of the traverse stage.

Although the mistress's language is less gynecological than the wife's, both are the Edna O'Brien woman par excellence – a martyr to her own sensuality, shrieking and wriggling on the cross.

Pauline (excellent Terry Norton) tells Clarissa (too- demure Orla Brady) that she has seen off previous lovers with her mature tolerance and deep knowledge of male psychology: "Every sensitive man loves two women, mamma mia and mamma whore." She says that, like the others, Clarissa will end up telephoning hysterically in the middle of the night, but Pauline and Henry will "snuggle up to each other in the dark, man and wife against the enemy outside." Not that Pauline can't be a scarlet woman, too – she has only to murmur, "I've never had to fake orgasm," and men leap on her, panting. But when Henry embraces Clarissa, she says, he "crushed my ribs so badly I had to wear a truss."

Henry leaves Pauline ("He is my life! My rock!") and their daughter, Brandy ("I'm his princess!"), who visits Clarissa and slaps her face. The mistress, however, has sorrows of her own: "When I told him, his face froze. He said: 'You've got to get rid of it.' Whenever I saw a mother and baby on the street, I burst into tears."

Pauline has a castration fantasy about Henry, which is symbolically fulfilled ("He's got a block"), and forces a kiss on Clarissa, who is strangely moved: "For one second I yielded. I was unfaithful to him with his own wife." Henry ditches both of them, but, while dallying with a third, is destroyed by the biggest female symbol of all: "The sea, the sea! His clothes on the bank, folded!"

Everything about this trite material – the sexual swagger, vindictiveness, masochism – speaks not only of the self-glorifying exhibitionism of the Sixties and Seventies but of an overwrought adolescent's desire to shock. Like such a teenager, Triptych cares less about being truthful than theatrical, but the play is too predictable and earnest to be either.

To 10 May (0844 847 1656)