The healer, his wife or his manager? As the push and pull of Faith Healer demonstrates, there's a power of difference between a monologue and a one-man show

Observer

There are myriad reasons to see the Almeida's fine revival of Faith Healer. Here are some of them.

Most plays simplify: the idea of drama as combat seems to demand it. But Brian Friel provides something genuinely complicated. Faith Healer is a Houdini-like feat of escapology: just as you think you've got the noose of meaning around a theme, it slips away, or changes into something else.

In a series of monologues, three characters - the healer of the title, his wife/mistress (they disagree on what she was) and his manager - look back on years of travelling, squabbling and suffering together as they hawked the healer's gifts through the Celtic bits of Britain. Each of their accounts undercuts the last: each supplies a different version of every pivotal event. The hero may be a charlatan; he may also be inspired: he doesn't know, and not knowing is a torment to him and to everyone around him. His precarious gift sometimes has aspects of a Christian mission - the play ends with a return to Ireland which is a road to Calvary. But more often this gift looks like the defining power of a writer's talent, a dramatist's flair. This is a play that could be seen as an approach to an autobiography.

To see Faith Healer now, more than 20 years after it was first staged, is to have a piece of theatrical history explained. Here is the wellspring of the Irish monologues that have refreshed the language of the British theatre over the past decade. You don't need faith, just ears and eyes, to recognise in Friel - the dramatist from Omagh who is in his seventies and the author of more than 20 plays - the godfather of Sebastian Barry and Conor McPherson.

Then there's the thrill of seeing an actor totally, dazzlingly remake himself. Before this, you might have thought that Ian McDiarmid (one of the outgoing artistic directors of the Almeida), directed here by Jonathan Kent (the other outgoing director), would always be recognisable by his spiky phrasing and his dancing gestures. Not so. As he delivers the central, wonderfully funny riff of the evening, he gives a brilliant display of comic spivviness - and touching seediness. It's the most surprising shift, the most complete makeover since Olivier turned his back on beautiful grandeur to play Archie Rice.

Kent's production sweeps through the play without an interval - rightly suggesting that the three characters are all part of the same enterprise. Between scenes, a tatty red plush curtain seems to drag itself across the stage, as if tugged by an invisible hand. One by one, the characters are discovered - looking as if they'd been waiting around for years - on a patch of a large, bare floor with shadows chasing around its edges. Rob Howell's design - a barn-like, dusty arena, with a grey light drizzling from a grubby window, and an Elastoplast-coloured poster advertising 'The Fantastic Francis Hughes, Faith Healer, One Night Only' - conjures up the chilly village halls in which the main character practises his art. But it also uses the spectres that are the strength of the King's Cross Almeida, itself a building that has been rescued from disuse.

Geraldine James is graceful, though not powerful, in the most difficult role: as the posh bird who runs off with the healer. As that healer, Ken Stott - though first-night tremulous - has the right combination of settled sneer and battered anxiety. All three actors do the essential thing of appealing directly to the audience, so that everyone watching feels complicit with these shifting versions of the truth. You become, in fact, like the eager visitors to a faith healer: you don't know how much is performance; you want to believe it's true.

There's a big difference between a monologue and a one-man show. Sakina's Restaurant - written and performed by Aasif Mandvi - is definitely a one-man show. It's designed to display the performer rather than his material. And the material is so skinny and whimsical that Mandvi's energetic gyrations and face-pullings - seen in all-too-much detail in the tiny Bush auditorium - look like attempts to disguise the fact that nothing much is going on.

There are few surprises in this story of a young man who leaves India for New York, where he settles with relatives struggling to assert themselves as Asian Yankees. Mandvi - who will soar to prominence when he stars in the movie version of V.S. Naipaul's The Mystic Masseur - ably supplies a series of rapid portraits: flicking an imaginary sari into place as a disappointed wife; snogging vigorously as her daughter; gibbering excitedly as an unruly young son. But not one of the characters is more than a cute caricature.

This is just the sort of show that the Bush doesn't normally do, and shouldn't. It suggests - unusually in this theatre - that smallness of space means shortness of reach.

Passe Partout's Progress in Flying Machines, on the other hand, could only have started out at BAC, where big ideas spring out of alcoves like jack-in-the-boxes. This collection of stories about flights - both physical and emotional - meanders and jerks as it switches from jokes to romance, but it's scattered with its own magical stardust.