Macbeth, Shakespeare's Globe, London; <br></br>Inconceivable, West Yorkshire Playhouse, Leeds; <br></br>Blackbird, Bush, London

The Scottish play is ruined ­ just like that!

External links

Globe theatre online

West Yorkshire Playhouse online

So foul and fair a day I have not seen. Thus Macbeth famously remarks as he surveys the meteorological situation on the witches' heath. Of course, Shakespeare's tragic hero is also forecasting his own destiny with its fickle mix of crowned glory and regicidal guilt. Unfortunately, when Jasper Britton's Macbeth utters those words at the Globe, they sound like a comment on the wildly oscillating calibre of Tim Carroll's production.

On the upside, his young leads are two outstanding classical actors. Britton and Eve Best (playing Lady Macbeth) are an electrifyingly natural couple. Physically, they're passionate and tender, she habitually folding her long arms around him. Psychologically, in both of them insecurity is woven with eager ambition.

Britton is at once palpably terrified and calculating. An intelligent Macbeth ­ albeit not a credible heavyweight soldier ­ he weighs up the pros and cons of murder with riveting lucidity. Best is even better. In her silver sheath dress, she's sinuous but also a slip of a girl. Instead of acting the hardened virago she is startlingly sympathetic, being ­ at first ­ innocently overjoyed by auguries of promotion. Her nerves are more likely to quiver or snap than be steely.

But what surrounds this pair? Phenomenally silly directorial concepts. One might appreciate a Globe production that shrugs off strict Renaissance costuming, but evening dress makes nonsense of all the battle talk, and the symbolic fights are preposterous ­ dapper chaps tossing talismanic feathers.

Meanwhile, the witches are reduced to joke-magicians, prancing to jazz in fez hats with all the supernatural menace of Tommy Cooper. Britton, supposedly in their thrall, is obliged to wail that his blood-drenched hands are plucking out his eyes while drawing gold tinsel out of a bucket. This just looks like ritual humiliation for a fine actor. Though the Globe remains a charming wooden "O", Mr Carroll puts the "dire" in "director".

Over at the West Yorkshire Playhouse, a less convincing married couple than Britton and Best take centre stage in Inconceivable. This is Ben Elton's comedy about fertility treatment, recently made into the negligible movie Maybe Baby, but here re-adapted from the novel by stage director Laurence Boswell.

By rights, our protagonists Sam and Lucy ­ who grow increasingly desperate to have a baby, but find medical exigencies decimating romantic love-making ­ should be strikingly real. After all, Inconceivable is based on a episode in Elton's own life, and Duncan Bell's Sam (though no Elton impersonator) starts writing a script called Inconceivable that goes on to be filmed.

In practice, though, Elton's urge to produce popular entertainment shallows out Sam and Lucy's troubles. The gentle-voiced Bell and gamine Geraldine Alexander (playing Lucy) are both good actors and offer flashes of genuine grief, but they're joined by dreadful caricatures. Playing Sam's BBC boss Nigel as a monstrously snarling exec, James Duke makes Berkoff look subtle. Elton's repartee can be lame, too: "I've seen harder knobs on the door of a bouncy castle" etc.

Still, Boswell knows from his previous production of Popcorn that Elton's work can be souped up impressively with stylish visuals. Designer Jeremy Herbert creates home and office interiors using chic projected backdrops. And Boswell is playfully inventive, having gynaecologists popping out of trapdoors. A less canny director could have realised Inconceivable as a dull sitcom.

Infinitely better writing can be found in Blackbird at London's Bush, a terrifically impressive British debut for new US playwright Adam Rapp. Froggy and Baylis are two wrecked drifters in a New York squat. Besides being a runaway delinquent, stripper and coke addict, Froggy is dying of hepatitis. Baylis is a Gulf War vet who wanted to make it as an artist but is now impotent and incontinent, staggering around swigging whiskey and threatening violence. Nonetheless, on some level, they care for each other.

Blackbird could, in the hands of a lesser dramatist, be a crude mix of in-your-face grunge and sentimentality. Rapp occasionally comes close to that, but steers clear. You might also think it sounds like another Trainspotting ­ or maybe La Bohème for the junkie generation. Actually, the squalor here is both appalling and cryingly funny, and Rapp has a brilliant ear for talk.

Director Mike Bradwell's American actors are also superb. Paul Sparks's tattoo-strewn Baylis is both dangerous and extremely amusing, getting in a savage temper as he mops up bodily fluids. And young Elizabeth Reaser ­ a serious star in the making ­ combines vitriol and fever with an unspoilt sweetness that's heart-rending. Not to be missed.

'Macbeth': Shakespeare's Globe, SE1 (020 7401 9919), to 22 September; 'Inconceivable': West Yorkshire Playhouse, Leeds (0113 213 7700), to Saturday, then Theatre Royal, Plymouth (01752 267222), 20 to 30 June; 'Blackbird': Bush, W12 (020 7610 4224), to 7 July