Wig Out!, Royal Court Theatre, London; In a Dark Dark House, Almeida Theatre, London

These trannies and their grannies are a real drag

Exclamation marks are always a bad sign. You feel that the publicity agent who described Olivier's Hamlet as "the story of a man who couldn't make up his mind" would have added one in. Wig Out! is the story of men who can make up their make-up and triumph on bad-hair days. "Like the South," drawls Rey-Rey, Mother of the House of Light, "I shall rise again."

There's a gay club in London called Heaven, no doubt part of the same Miltonic cosmology created here by the black American playwright Tarell Alvin McCraney: the House of Light is at war with the House of Diabolique, with a fashion showdown booked on the catwalk at the Cinderella Ball.

A minimal narrative momentum is supplied by the induction of Eric the Red (Alex Lanipekun) – a non-cross-dressing gay boy – in the trials of transvestism. Trouble is, these trials are nonexistent beyond the queeny caterwauling of the inmates and the minor emotional rivalries in the House.

Rey-Rey's opposite number, Serena (Billy Carter), a masochistic devil woman, scowls in the outer darkness, while her henchman Loki (Drew Caiden) dances like a demon. Lucian, founding father of the House of Light, is, I suppose, the brightest star who fell, but Danny Sapani plays him as a grumpy doorman at a buffet bar.

McCraney is this year's new name, a Harvard graduate promoted by Peter Brook, whose two poetic Louisiana meditations mixed with Yoruba mythology at the Young Vic, The Brothers Size and In the Red and Brown Water, have deservedly won him the Evening Standard's most promising new playwright award. But Wig Out! seems strained and anorexic, and not just because the boys are stick-thin clothes horses.

Dominic Cooke's production, designed by Ultz, has ripped out the centre of the Court's stalls area and installed a raised catwalk. The music blares anonymously through the smoky ether, the proceedings supervised by a singing girl group, the Fates Three, and broken up with confessional gender-bending monologues, all of which begin, "My grandmother wore a wig..."

Cooke's voyage through the underground is devoid of informative travel notes – such as, what exactly is the culture of black American sexuality we're dealing with here? – and, more importantly, any showbiz uplift. It's all deadly dull, apart from Kevin Harvey's camp put-downs as Rey-Rey, an act of diminishing returns in a thin text, and the elegant pouting of Nathan Stewart-Jarrett as the ballroom queen who picks up Eric on the Subway.

At least Wig Out! has one thing in its favour: it's probably the only new play this year not (directly, at least) about child abuse. In a Dark Dark House at the Almeida is a grimly personal exorcism by another American writer, Neil LaBute, of an unhappy childhood at the hands of a violent father. Two brothers, one a successful lawyer, Terry (Steven Mackintosh), the other a sullen security guard, Drew (David Morrissey), learn the truth about each other by sharing what is secret between them.

LaBute confirms his mastery of form and narrative revelation in a piece that is slyly composed as a taut triptych in thrall to Sam Shepard and Ingmar Bergman but still feels undernourished, despite the careful attention of the director, Michael Attenborough.

Mackintosh gives a wonderful account of an adulterated adulthood that, despite the compensations of family life, has spun out of control into drink and promiscuity. Morrissey reminds us of his power and naturalism on stage and finds new notes of vulnerability.

Lez Brotherston's design is a paradisiacal green enclave serving first as the grounds of an institution, then a novelty putting green, finally Terry's back garden. In the middle scene, Drew encounters the daughter of the brothers' sexual nemesis, a lush little Lolita played by Kira Sternbach as a reminder of the possible joys of sex. But Eden is a tainted place. The apple has been munched. And these boys obviously didn't have a granny in a wig.

'Wig Out!' to 10 January (020-7565 5000); 'In a Dark Dark House' to 17 January (020-7359 4404)