THEATRE / The story of a crazy mixed up kid: Paul Taylor reviews English Touring Theatre's Hamlet at the Donmar Warehouse

But I have that within which passes show,' claims Hamlet, and the best Hamlets manage, through one of the paradoxes of acting, to show that this is true - no matter how outre or frenetic they make the character's antic disposition. Mark Rylance, the outstanding Hamlet of our times, kept veering into behaviour that was ostentatiously barking, yet convinced you that his pyjama-clad lunacies were somehow seamlessly consistent with an injured spirituality. Alan Cumming, who assumes the role now in Stephen Unwin's English Touring Theatre production, is a dazzling performer who excels in showy, limelight-hogging parts like his madman with the calculated identity crisis in Accidental Death of an Anarchist or Valere, the self-infatuated playwright who gambolled about David Hirson's La Bete, making your average Restoration fop look like a tongue-tied shrinking violet.

The subversive, ludic side of Hamlet is, therefore, well within his range; so too, it turns out, is the crazy mixed-up kid. With his spidery legs ballasted in big black boots, his waif-thin form stripped down from velvet doublet and hose to Lycra cycling shorts and outsize black T-shirt, he cuts an arrestingly ambiguous figure - part precocious yet pained urchin; part pale, mischievous fool - a role which Cumming's narrow, beaky, seditious features might have been expressly carved to fill.

What he fails to communicate for me, though, is any real sense of the speculative interior life of this hero who cannot act for 'thinking too precisely on th'event'. If punching your head frantically every time you made reference to the mind were a guaranteed method of suggesting self- thwarted intellect, then Cumming, in whom this response is virtually Pavlovian, would be the greatest Dane of them all. But, in fact, it just looks like a case of protesting too much. Busily external, with loud gear changes as his moods shift, Cumming's Hamlet isn't helped either by the fact that he plays so directly to the audience and rarely seems to be communing with himself.

In Unwin's undistinguished production, Elizabethan elements collide with modern ones (the players are portrayed as New Age travellers; the useless 'little patch of ground' that Fortinbras goes to war over looks suspiciously like the Falklands from the footage we're shownon a laboriously lugged-in television), but it produces no startling illuminations. The best performances come from Pip Donachy as a Claudius who, towards the end, gives the evening's most haunting glimpse of innerness, and from Trevor Baxter's balefully comic Polonius, who here, rather too fittingly given his penchant for spying, eventually gets it in the eye.

Continues until 27 November at the Donmar Warehouse (Box office: 071-867 1150)