The Private Room, New End Theatre, London

With substantial roles for only two characters, Mark Lee's drama sets itself a task that would be difficult with a cast of hundreds: "trying to understand the fear and pride that have pushed my country down a very dark path."

With substantial roles for only two characters, Mark Lee's drama sets itself a task that would be difficult with a cast of hundreds: "trying to understand the fear and pride that have pushed my country down a very dark path." Lee, a foreign correspondent as well as a playwright, has set half his play in Wall Street, half in Guantanamo Bay, where suspected terrorists are interrogated. But, despite some deft writing and the horror that recent revelations have added to the prison scenes, the play is no more engaging emotionally than it is intellectually. Eschewing argument for analogy and impressionism, it becomes, finally, sentimental.

For about half its length, though, The Private Room seems a much better play, thanks to Debra Hauer's classy production. George Souglides' set - a blown-up photo of barbed wire backing a stage divided between a chic, minimalist restaurant and a clinical interrogation cell - is elegantly ironic. Michael Hayden gives an impressive performance as Lawrence, a trader whose handsome face remains benign while his mouth spews hatred and contempt. There is also an excellent cameo from Bernice Stegers as a restaurateur whose deference to Lawrence shades into chilly reserve, then threat, as his unpaid bills mount. Janet Kidder, though, is too insistently innocent as Barbara, the young trader from a lower-middle-class Irish background who pits her stern morality against Lawrence's success and ruthlessness.

An army reservist, Barbara spends a year in Cuba, and manipulates Salman, a meek Pakistani, into giving her the names of his kinsmen. Her scenes alternate with monologues by Lawrence, who complains about his fading marriage and pulling power ("Used to be stockbrokers got laid. Now it's firemen."). Presumably Lawrence represents the heartless capitalist machine driving Barbara's harsh tactics. But the girlish Kidder is less scary than many an infant-school teacher, and Lawrence is given a speech in which he reflects sadly that building a fence ("something real") gave him more satisfaction than making millions. One looks around for the puppy.

This parade of mushiness and caricature is ended with Barbara's return to New York, declaring that Guantanamo made her realise, "I'd never thought about the kind of person I wanted to be." She decides to renounce her job (ruining Lawrence in the process) because, though she never broke any rules, she knew illegal trading was going on and winked at it. What is the message here? That the honourable path is one of self- immolating purity?

The Private Room has a fine title, symbolic of power, secrecy and conscience, but the vagueness and naivety of its writing don't live up to it.

To 26 June (020-7794 0022)