THEATRE: Cracked Hampstead Theatre, London

Inspired by the experiences of the dramatist's brother-in-law, who was an army psychiatrist during the Gulf War, Daniel Hill's Cracked focuses on a "Battle Shock Recovery Unit" that is dumped in the desert with one (inconveniently green-coloured) tent, no supplies or facilities and told to expect 100 casualties a day. Only one man shows up, which is just as well for, by that stage, you would need a long course of psychiatric care after you'd received psychiatric treatment at the hands of this disintegrating, gallopingly dysfunctional bunch.

It takes a bit of believing that such an ill-assorted group of shrinks and nurses - including a Glaswegian Territorial Army fiend and behaviourist bully (Nigel Terry), an ex-Para and Broadmoor Nurse (Vincenzo Nicoli) and a weedy walking disaster (Mark Hadfield) - would be assembled and expected to perform tricky, vital tasks together after a mere eight days rather than the eight months normally required to weld these units into a therapeutic "family".

Realistic as individuals, the men, as a company, have an incompatibility that borders on the cartoon-like. This underlines a certain indecision in the play. Parts of it seem to be aiming at the painstaking detail of docudrama. Having been cleared by the MoD, Hill apparently undertook a year's research. With the proceedings regularly becalmed while the men launch into autobiographical orations that are seemingly angled more at the audience than at their colleagues, Cracked often feels weighed down by the fruits of this fact-finding mission. Hill's own experiences as the father of an autistic child are also given voice, movingly, lengthily but with insufficient dramatic justification, in the speeches of David Horovitch's doleful, witty Brummie major.

The parts I liked best, though, were those where the play came nearest to working as a savagely satirical metaphor for the kind of supposedly vanity-inducing operation that is itself insane. Cracked has a trick opening - a First World War trench scene with a Tommy being ordered at gun-point to take his yellow bollocks back up the line - which turns out to be part of an army demonstration of how the treatment of battle shock has changed. Nowadays, as we see here, the approach is to offer counselling in a "family" atmosphere near to the field, which plays on the soldier's loyalties to the "operational family". But how genuinely caring is this treatment? In a climactic confrontation with Anthony Clas's haplessly liberal public school major, the no-nonsense Glaswegian cuts the crap: humanitarian aid is not the business they're in, "but manpower preservation and re-supply. It's about sending them back to plug the gap and be killed." Even in purely psychiatric terms, there's a contradiction - for to what degree can mental adjustment to the derangement of war be considered sanity?

Terry Johnson's well-acted production, with its film projections of zooming fighter planes and its unnerving sound effects, finely captures the balance, in war, between edgy tedium and high tension. But the play, which demonstrates Hill's genuine dramatic promise, never develops enough mad momentum to do justice to the organisational and conceptual lunacy it depicts. I suppose this amounts to saying that I wish it had gone out more to do for shrinks in a war-zone what Joe Orton's What the Butler Saw does for them at home.

Booking: 0171-722 9301. To 17 May Paul Taylor