The Late Middle Classes, Donmar, London <br />The Crucible, Regent's Park, London <br />Joe Turner's Come and Gone, Young Vic, Llondon

Simon Gray's study of a gay piano teacher and his pupil features a virtuoso performance by the child

Lou Ford, the anti-hero of The Killer Inside Me, is a nasty piece of work, and Michael Winterbottom's film is a nasty piece of work too.

According to the annals of theatre history, The Late Middle Classes is Simon Gray's "lost masterpiece". This intimate memory play – depicting a pubescent boy and his closet-gay piano teacher in provincial, postwar England – was cruelly denied a West End run in 1999. Its Watford Palace première – directed with a subtle intensity by Harold Pinter – was promised a London transfer, then ditched in favour of a shoddy boy-band musical.

Now, with Robert Glenister as the stewing teacher, Mr Brownlow, and Helen McCrory the boy Holliday's self-centred mother – the ultimate frustrated housewife – it's very tempting to hail director David Leveaux's new Donmar revival as a great play properly recognised at last.

Truth be told, though, I'm not quite so impressed this time round. What remains sharply unsettling about Gray's domestic drama is how it portrays every character's private life as a tissue of accumulating little lies – even in a household that supposedly favours frankness.

We learn that Holliday's pathologist father, Peter Sullivan's tweedy Dr Smithers, and McCrory's sporty Celia, made a marital oath to be "straight" with one another. However, at least one of them has become a covert adulterer and, even after a fraught confessional row, the extent of that deception remains hazy.

Meanwhile, both have taken their eye off the ball regarding the relationship that Glenister's furtively desperate Brownlow is fostering with their son. For starters, he suggests lessons at his house, where he resides with his angst-ridden, Viennese emigrée mother (Eleanor Bron). Then he orchestrates an overnight stay with the boy in London.

The best performance here, startlingly, comes from the child actor Laurence Belcher (appearing in rotation with two others). His Holliday is extraordinarily natural, perfectly capturing the demure politeness of an old-fashioned, well-brought-up child who has learnt to bite his tongue. When his father suddenly, belatedly, suspects Brownlow of sexual abuse, the boy responds to a grilling with what might be – it's scarily impossible to tell – either total innocence or unblinking elaborate fabrication.

The trouble with the production is that, despite the complexity of Dr and Mrs Smithers, their starchy chats tilt into dated comic cliché, especially Sullivan's extended bumbling over the birds and bees and McCrory's accelerated flurries of plummy exasperation. The tone, when satirical, rings slightly false. Doubling as a patently bitter adult Holliday, Sullivan also undermines Belcher's more delicate ambiguities. Still, cavils aside, this is a commendable revival of a minor classic, and better late than never.

Any such sexual indiscretion in 17th-century Salem would, of course, be punished severely. What's terrifying in Arthur Miller's communal tragedy The Crucible is how one undisclosed fling – between the earthy farmer John Proctor and dangerous wild-child Abigail Williams – spirals into a vortex of destruction, driven by petty vendettas, paranoid fundamentalism and an injudicious court.

This may seem sobering fare for the picnicking punters of Regent's Park. Yet Tim Sheader's production is powerfully assured and tense, played out on the fallen façade of a black, clapboard house, so its portal and shuttered windows operate like sinister, glowing trapdoors. The elders in Sheader's cast are particularly splendid: Susan Engel as the wrongfully imprisoned, fearlessly dignified Rebecca Nurse; and Oliver Ford Davies as the presiding judge, Danforth, whose air of sagacious gravitas inspires glimmers of hope, repeatedly dashed.

Patrick O'Kane's John Proctor has, it must be said, his hammy moments, straggly-haired and staggering around in chains. And Emily Taaffe's Abigail is put in the shade by Anni Domingo as the cornered, fast-thinking Barbadean maid, Tituba, the first to be accused of devil-worship. All in all, though, a fine ensemble.

The Young Vic's artistic director David Lan is also on top form, staging Joe Turner's Come and Gone from August Wilson's epic cycle of Pittsburgh plays, which depict the African-American experience throughout the 20th century. This one is set in the second decade, circa 1911, in a boarding house presided over by a soothing maternal landlady, Adjoa Andoh's lovable Bertha, and her comically penny-pinching husband, Danny Sapani's Seth.

The set is a wide circle of red earth that feels instantly intimate, surrounded by the audience and scattered with a few sticks of furniture: a stove and a sink here, a double bed there.

Tensions rise in this household when a slave from down south arrives in town, obsessively determined to track down his runaway wife. Seth doesn't care for this morose stranger, Herald Loomis (Kobna Holdbrook-Smith). Nor does he appreciate the hallucinatory fit Loomis has – jabbering about walking bones – when he comes under the spell of another resident, Bynum (Delroy Lindo). The latter is an old "conjure man" who potters about in the garden drawing magic circles, sacrificing pigeons, and trying to help lost souls "rediscover their song".

Personally, I was completely at sea with the mystical stuff, but it's thrillingly pulled off by Lan's ensemble, with a quietly powerful performance by Lindo. Elsewhere, Joe Turner's Come and Gone rambles enjoyably, its dozen or more characters wandering in and out, the more grounded warmly dispensing advice around Bertha's kitchen table. Nice work.

'The Late Middle Classes' (0844-871 7624) to 17 Jul; 'Joe Turner's Come and Gone' (020-7922 2922) to 3 Jul; 'The Crucible' (0844-826 4242) to 19 Jun