The Earthly Paradise, Almeida Theatre, London

Three's a crowd in paradise

Peter Whelan is a dramatist one associates with humane, well-crafted, meticulously researched plays, and with a gift for entering widely diverse worlds - ranging from the dangerously free-thinking milieu of Christopher Marlowe, in The School of Night to the tensions of the pre-Wall Berlin of 1950, in A Russian in the Woods.

Peter Whelan is a dramatist one associates with humane, well-crafted, meticulously researched plays, and with a gift for entering widely diverse worlds - ranging from the dangerously free-thinking milieu of Christopher Marlowe, in The School of Night to the tensions of the pre-Wall Berlin of 1950, in A Russian in the Woods.

Focusing on a painful ménage à trois involving two of the Pre-Raphaelite Brotherhood, his new work, The Earthly Paradise, offers some of the customary satisfactions of the Whelan oeuvre. But, to my mind, it's his weakest piece in some time. For much of the first half, it feels strangely pointless. You certainly absorb much intriguing information, but you may reckon that you'd be just as well off curled up at home with a biography of these people.

The sense that the piece has difficulty rising from the runway of exposition into the clear air of theme and metaphor is not lessened by its reliance on direct-to-audience narrative address from the poet, designer and socialist William Morris.

To be sure, the material is not without fascination. Set at Kelmscott Manor in the early 1870s, the play traces the tensions in a peculiar triangular relationship. We see Morris heading off for Iceland each summer, leaving his wife, Jane, an ethereal beauty of working-class extraction, free to be the model, muse, soulmate and (as he mistakenly believes) bed-mate to his great friend, the artist and poet Dante Gabriel Rossetti. It was Rossetti who discovered Jane and who might have married her, had he not been engaged already.

Bringing him into contact with a bracing culture where people live out their socialism and where women are not the chattels of men, the Icelandic trips alert Morris to what is false about the supposed ideals being served at Kelmscott. Medievalism may have been the spur to the political dimension in the Pre-Raphaelite movement, but it has a terrible effect on the emotional world of this trio, encouraging them (in Jane's words) to live "as though characters out of a storybook - a high romance". The men impose on Jane the persona of a tragic medieval queen and, in purposely assuming the role of the cuckold Arthur to the Lancelot and Guinevere of the other two, Morris indulges in a gesture of self-sacrifice that rebounds disastrously. Far from freeing the pair to form a creative physical union, it encourages in Rossetti a neurotic desire for a pure Dante-and-Beatrice-style relationship and pushes him down the road to paranoid madness.

Having come across as civilised drama in search of a real reason for existence, The Earthly Paradise then perversely starts to spell out its themes with such a thudding over-explicitness that you seem to be getting a play and the Coles Notes rolled into one. This is a shame, because Robert Delamere's touching, beautifully designed production boasts an outstanding performance from Nigel Lindsay, who presents Morris as a wonderful wounded bear of a man. Saffron Burrows is all highly strung bewilderment as Jane, and Alan Cox skilfully charts Rossetti's decline from whimsical dandy to delusional wreck. It's not their fault that the drama remains stubbornly remote from current concerns.

To 8 January (020-7359 4404)