He was already one of Britain's hottest young directors. And his reputation won't suffer with his latest production
You can tell something is up from the entries in the programme. A note informs us that Hamlet, the new flagship production at the RSC, directed by the hottest young director of the moment, has been "specially cut and partially restructured". Five children are credited in the cast list. The party guests are played by the citizens of Stratford. And Rik Statman for King Key Movies (UK) has directed the film sequence. Hang on, you think: what children, what party, what film sequence? They were never in my edition.

But there's no need to panic. The director Matthew Warchus has brought together the designer, composer and lighting designer with whom he had such success in Art. Far from introducing a ragbag of attention-grabbing gimmicks, they have acted as thoroughly and decisively as the British electorate. This Hamlet is a landslide event which gets rid of half the old characters. In this streamlined Art-house version, there's no Marcellus, Barnardo or Francisco, no Reynaldo, Voltemand or Cornelius, and no sailor, messenger or second gravedigger. There's no Norwegian prince, captain or army. There's no Norway, in fact.

What there is, is pure Danish, and it works extremely well. As Hamlet, Alex Jennings appears centre stage, holding his father's ashes in an urn, while on the screen behind we see black and white footage of the father playing in the snow with his son. Over the speakers, we hear the words of the usurping king, Claudius: "Though yet of Hamlet our dear brother's death the memory be green ... " In this strongly personal production, which axes the public-political side, Hamlet's memory of his father, the motive for revenge, never loses its freshness.

The first big scene is the wedding party in a marquee. No, you may not remember it either. The gravel-voiced Claudius (Paul Freeman) puffs on his cigar and dances with his new wife Gertrude (a pragmatic Diana Quick, replacing the injured Susannah York). But the talk is familiar. Claudius gives Laertes (William Houston) leave to go to France. Polonius (David Ryall) offers Laertes paternal advice, and when Ryall dances with his daughter Ophelia (Derbhle Crotty) he takes the opportunity to warn her that Hamlet is a bit posh for her. Half of the first half has been jumbled about and relocated here.

As Hamlet, Jennings looks like a sensitive Wall Street banker. The fact that he is wearing a black suit doesn't look much of a gesture of defiance as this is a black-tie evening. He wanders round taking the Polaroids with which he will later confront his mother in the sheet-sniffing scene. Into these wedding celebrations, amid champagne, fireworks, balloons and bridesmaids, walks the ghost of Hamlet's father (Edward Petherbridge). He doesn't clank around in heavy armour or boom out his news in stentorian tones. Petherbridge enters in a smoking jacket, speaks with quick authority, then drifts away, like a guest in search of some breakfast.

Jennings soon swaps his suit for a vest, braces and overcoat, and carries around a paper bag containing a revolver. In an attic crowded with old trunks he turns it caressingly to his skull and considers suicide ("a consummation devoutly to be wished"). He's a modern ironic figure who uses similes and metaphors as jokey forms of hyperbole, as if he can't quite be completely serious about something this important. There's a clarity and energy here that silences the usual anxieties about updating a classic from the time of Elizabeth I to Elizabeth II. Jennings hugs Crotty, then pushes her away, stubs his cigarette out on the floor and tells her to get to a nunnery. There's a whole new spin to her saying he's blasted with "ecstasy".

Jennings wittily directs the players who are about to perform to the King and Queen with the camp impatience of a director. The play-within- the-play is a stunning sequence performed in graphic silhouette behind a sheet: a superb combination of Warchus's direction, Hugh Vanstone's lighting and Mark Thompson's design. Gary Yershon's buoyant music gives a momentum to the scene changes, as it did in Art. There are other similarities too: the scenes are ruthlessly clean and uncluttered, yet within them Warchus and Thompson build up rich group dynamics. Warchus also handles transitions (as he did with Peter Pan at Leeds) with sureness and fluidity. Only one prop slips out of his control. Paul Jesson is excellent as the sandwich-munching gravedigger, but Yorick's skull has a life of its own and rolls off the stage into the audience. Someone has to hand it back.

The American playwright Terrence McNally attended classes given by Maria Callas in the early 1970s and was struck by their theatricality. His play Master Class, a hit in New York, opened this week in the West End, with Patti LuPone, last seen here as Norma Desmond in Sunset Boulevard, playing Callas. LuPone strides on, in a black trouser suit, her hair swept back, with bright lipstick and thick mascara, and lectures us while striking a series of statuesque poses. One thing we are going to need if we want to be opera singers is a look. "I don't see anyone out there with what I consider a look," she tells us. That's a bit tough on a first night audience that includes Jerry Hall. For budding singers the main Callas/ LuPone advice is: 1 Make an entrance. 2 Look good. 3 Don't be sad, be tragic. 4 Don't be happy, be delirious. 5 Make an exit.

Like the Sian Phillips vehicle Marlene, Master Class is a one-woman show with one or two other people involved. There is a tall New Zealand soprano who is trying to do her "bist", a hunky tenor who wants to get some "feedback", and a smiley young woman who is hoping to pick up some "temperament". LuPone is emphatic, bitchy and flamboyant. We don't hear her sing but we can see that she is loud. It's the students who perform arias from Bellini, Verdi and Puccini. LuPone interrupts, cajoles, patronises, gossips and namedrops. "Luchino" is Visconti, "Ari" is Onassis, and "Darling" is someone she has only just met.

When McNally exhausts the comic possibilities, he moves Callas deftly into the spotlight as she talks us through the big scenes in her professional and personal life. LuPone gives a commanding performance, rolling her eyes to the audience or holding out her chin with an expression of such impassivity that it should appear on a stamp. She more than matches her own advice to dominate the audience. McNally gives her lots of smart lines. But the format is constricting and - unlike his subject - it keeps hitting the same note: theatrical it may be, dramatic it isn't.

Moira Buffini's play Gabriel, presented by the Soho Theatre Company, was a deserving recipient of last year's winner of the LWT Plays on Stage Award. Buffini sets her play in occupied Guernsey in 1943. The island is rich in moral ambivalence. Everything is grey, except for the market which is black. The Germans consider Guersney to be a cushy number; its inhabitants' Resistance is low. For Jeanne Becquet, an attractive middle- aged mother, played by Lisa Harrow with a smart sense of self-preservation, her resistance is lower than most. She is visited by local Nazi officer, Von Pfunz, a scary comic figure played with gleaming gusto by Philip Fox.

A handsome young man is found washed up on the coastline. He speaks English and German fluently but he has lost his memory. Who is he? This absorbing play wobbles occasionally in its staging (the stabbings, seductions, surprise entrances), but it is an ambitious subject, intriguingly handled.

'Hamlet': RSC Stratford (01789 295623). 'Master Class': Queens, W1 (0171 494 5040). 'Gabriel': Soho Theatre Co, W1 (0171 420 0022), to 24 May.