Clair wakes up one morning with three layers of skin missing. The air crackles and she sees everything by lightening. Polly Wiseman's first play is an extraordinary account of bipolar disorder, or manic depression. Her writing sears and burns you too feel what it must be like in the manic phase - to be too bright.
But just as the manic depressive cannot sustain the manic phase forever, and eventually comes crashing down, so Wiseman cannot sustain writing of that quality. Her play is fired by anger at our Kafkaesque mental health system (those detained in psychiatrist institutions have fewer rights than those suspected of serious crimes) but it gets bogged down in the not very interesting relationship between the unit's middle-class idealistic doctor and her weary superior who no longer has the energy or the will to try and change things.
Joe Penhall's Blue/Orange looked in greater depth and with greater sophistication at medical and social attitudes to mental health, but Wiseman does it with more young fury. As Clair, the young girl detained for her own safety who gets assaulted on the ward, Lyndsey Marshal shines brightly, like a 1000-watt lightbulb on the blink.
Playwrights, like policemen, are getting younger these days, and the second offering in the Soho Young writers season, Playing Fields, comes from Neela Dolezalova, who was 16 when she wrote it. It bobs between the dreamy introspection of adolescence, when summer went on for ever and ever, and the clarity of the young, who know that the previous generation have fucked up and only they can save the world. Its heroine is Thyme, a sussed 16-year-old in a joyful lesbian relationship with Flea, whose one night stand with Justin causes ripples. What is interesting is its youthful optimism. Lisa Goldman's production taps into the play's rhythms and wit and makes terrific use of film; although Thyme and Flea seem too good to be true, you can't help feeling that, if the future is in their hands, we are going to be all right.
· Until November 2. Box office: 020-7478 0100.
