Piano Forte, Royal Court, London<br/>Tom and Viv, Almeida, London<br/>Fabulation, Tricycle, London<br/>Amadeus, Wilton's Music Hall, London

Mischief: a game for two to play

Background music comes to the fore in Terry Johnson's ultimately haunting new seriocomedy, Piano/Forte, where memories exert a vice-like grip on two messed-up sisters. Louise and Abigail's father, Oliver Cotton's Clifford, is a Conservative who clearly believes in moving on: a dapper politician who has survived a scandal by becoming a celebrity journalist. However, when he makes a rare visit to his ancestral pile with his new fiancée - a model called Dawn - he finds his delinquent daughter, Kelly Reilly's Louise, is bent on causing trouble.

Besides provocatively swanning down the staircase topless, Louise unlocks the grand piano beloved of her late mother - a depressive musician who is said to have committed suicide. Thereafter the nervous homebird, Alicia Witt's stammering Abigail, finds herself compelled to open its lid and play the old tunes while Uncle Ray accidentally leaves a shotgun lying around...

Piano/Forte has its weak and its clumsy patches. Initially, the passé look of the country house setting is a dampener, suggesting some creaky old murder-mystery. A few of the broader jokes - though knowingly outré - feel strained too. A skimpy, surreal subplot involves pornographic trapeze artists disguised as wedding-party servants, using dildos as water pistols. At other points the more serious set speeches can sound overwritten.

However, Johnson has things to say about emotional shackles and liberation, alter egos and destructive-protective impulses. The power games are potent and the audience is often kept on tenterhooks. This play is also the richer for being laced with echoes from stage and screen history, evoking Sleuth and Noel Coward's Hay Fever as well as, more poignantly, Friel's Aristocrats, Chekhov's Uncle Vanya and Strindberg's Miss Julie - a part Reilly previously played.

Here she is alarmingly convincing as a dangerous wild child, sexually flaunting but with vulnerability beneath the bitterness. In fact, all the performances are excellent, including Danny Webb's earthy, tender Ray and Natalie Walter's risibly dim but decent Dawn. Witt is also an outstanding pianist and her final scene without words - alone in the darkened house, playing Ravel's "Pavanne for a Dead Child" - is an extraordinary, ambiguous vision of loneliness or perhaps rhapsodic release.

At the Almeida, a fine line between painfully comic and tragic marital struggles is kept grippingly taut throughout Tom and Viv. Michael Hastings' biodrama about T S Eliot and his unbalanced, misdiagnosed and eventually certified wife, Vivienne Haigh-Wood, is revived by Lindsay Posner with Will Keen and Frances O'Connor superbly cast as the doomed couple.

Though inevitably not comprehensive, this chamber piece has a stark, neat structure. It is fluidly staged, with just a few chairs and pools of light on a parquet floor. With some new textual revisions, the action switches between reminiscences - principally inspired by interviews Hastings conducted with Viv's brother, Maurice - and flashbacks charting the course of Eliot and his in-laws' long-suffering but increasingly harsh treatment of Viv.

These flashbacks reveal troubling behaviour on everyone's part. O'Connor's Viv is a heartrending mix of sweet flirtatious charm and manic brio veering suddenly into paranoia and weirdly spiteful, desperate acts - not least pouring molten chocolate through the letter box of Eliot's office. She ends up, hospitalised, superficially calmer than anyone else. Keen's Eliot, meanwhile, is rigidly uptight - suit buttoned, hair plastered down - sometimes frosty and financially freeloading but with glimmers of agonised tenderness and his own moments of explosive impropriety. Keen's portrayal suggests the American poet developed an almost John Osborne-like love/hate relationship with the English upper classes. Hastings also raises questions about whether Eliot's growing religious faith supplanted his oaths of marital commitment.

A rotten husband wrecks Undine's career as a high-flying Manhattan PR in Lynn Nottage's African-American comedy, Fabulation. When Herve does a runner with all Undine's savings, she is forced to return to her long-spurned family in Brooklyn, bungles buying cocaine for her granny and finds herself on a compulsory rehab course. Then she learns folks on the skids can be kind. Frankly, this is a slight, stereotyped, satirical-turning-sentimental piece. Still, Indhu Rubasingham's revival is swish, brisk and bouncy. Jenny Jules' uppity Undine is supported by a particularly enjoyable cameo from Karl Collins as the smarmball Herve.

It's the professional rival who is hell bent on destroying the wild-child genius, Mozart, in Peter Shaffer's Amadeus. John Doyle has had great success staging musicals (like his Tony-winning Sweeney Todd) with multi-tasking actor-musicians, and this revenge drama-going-on-classical concert has a ghostly beauty. Doyle's ghoulish but elegant ensemble gathers in black tie on a stage decorated with gilded mirrors, lit by footlights. To his credit, Matthew Kelly is better than you might imagine as the seething mediocrity, Salieri. But the sad truth is that no one is dazzlingly brilliant here, theatrically or musically, and Kelly is encouraged to pull out all the stops in terms of Gothic melodrama, exposing the script's worst purple passages. Jonathan Broadbent's Mozart manages, conversely, to be mildly dull while Jess Murphy's Constanze makes her modern anachronisms ("Ta very much") even more excruciating with an ill-suited posh accent.

After the NT's embarrassing recent revival of Shaffer's The Royal Hunt of the Sun, one can't help concluding that all that glistered in the 1960s and Seventies was not gold.

k.bassett@independent.co.uk

*'Piano/Forte' (0207-565 5000) to 14 October; 'Tom and Viv' (0207-359 4404) to 4 November; 'Fabulation' to 21 October; 'Amadeus' (0207-702 2789) to 14 October