Three Days of Rain, Apollo Theatre, London<br></br>The Stone, Royal Court Downstairs, London<br></br>England People Very Nice, NT Olivier, London

James McAvoy returns to the stage as a man who uncovers his parents' past and finds echoes in the present

The dust is lying thick in this old converted warehouse in downtown Manhattan. The windows are begrimed, yet the emotionally volatile drifter, James McAvoy's Walker, beds down here in Three Days of Rain – Richard Greenberg's 1997 drama about parents and children, love triangles and legacies.

Walker's famous architect-father, Ned, held on to this back-alley bedsit for more than 30 years. It was the pad that he and his best friend, Theo, shared as budding co-designers. Walker has only just learnt this on reuniting with his sister Nan (Lyndsey Marshal) and with Theo's son Pip (Nigel Harman), for the reading of Ned's will.

On finding a long-abandoned diary, Walker resents his father's brief elliptical entries because he has bitter childhood memories of the man's failure to communicate. But the clock then spins back to 1960, letting the departed generation play out their youthful days. Ned is revealed, here, to be sensitive, ardent, and inspired – though increasingly tinged with guilt – as he falls for Lina, his buddy's girlfriend.

This is a play of two halves, and McAvoy's return from big-screen stardom to the West End stage is disappointing in Act One. On press night, he over-egged Walker's manic energy, so that the character got on your nerves.

The playwright's irksome habit of name-dropping doesn't help. Strewn with references to Hamlet, Oedipus and Hedda Gabler, the dialogue sounds like showing off. The director Jamie Lloyd should really have downplayed Greenberg's hammy inclinations too. Instead, bursts of eerie music accompany the creakiest moments – including Walker's ritualistic obsequies as he swathes himself in a dust sheet, toga-style, to immolate his father's journal. The dirt and cobwebs aren't the only things laid on thick here.

None the less, Harman has vibrant comic timing as the affectionate but exasperated Pip. And Three Days of Rain feels like a touching act of grace as it reverses through the decades to more fully understand those we have heard condemned. With the same three actors doubling as the progeny and their parents, Greenberg suggests a deep level of sympathy.

The play contemplates the kaleidoscopic nature of inherited characteristics, and Lloyd elicits increasingly multilayered performances. Marshal brings out the anxiety hidden behind Nan's steady air and Lina's surface high spirits. And McAvoy is achingly sweet as Ned, losing his shy stammer and relaxing at last when he wraps Marshal in his arms.

In a curious parallel, the past is also misconstrued in The Stone. However, in Marius von Mayenburg's damning chamber piece spanning several decades of 20th-century Germany, the younger generations keep recounting a cleaned-up, positively glowing version of their parents' actions.

The setting is a Dresden house haunted by its previous inhabitants. After living in West Germany during the Cold War, Helen Schlesinger's affluent Heidrun has returned to her childhood home. Her aged mother and adolescent daughter – Witha (Linda Bassett) and Hannah – accompany her but cannot settle peacefully.

Amanda Drew's surly Stefanie, an occupant in the Soviet era, materialises and accuses Heidrun of ousting her clan. Worse, flashbacks to Hitler's regime reveal that the family history – telling how Heidrun's father helped the preceding Jewish residents escape – is a shameful cover-up. Evidence of anti-Semitism has been swept under the carpet, or more literally buried in the garden.

The Stone marks the start of the Royal Court's "Off the Wall" season of new plays about Germany, chiming with David Hare's monologue, Berlin, at the National Theatre. It also fits the Court's on-going agenda of exposing the dark underside of the middle classes.

Frankly, though, Ramin Gray's production with its modish set – a glowing, doorless chamber with plastic chairs – can't conceal that the play is neither startling nor up-to-date (only taking us up to 1993). The formal experimentalism doesn't make for profundity either, intercutting snippets of frosty conversations from 1935, 1953, 1978, and 1993, in a stiff English translation.

To give the cast their due, Schlesinger has stern assurance, Bassett (no relation) has some hilariously batty senior moments, and Justine Mitchell burns with indignation as the Jewish housewife who troubles Witha's conscience. But trapped on stage, Gray's actors have to spend half their time staring into space. "I don't want to be here," grumbles Loo Brealey's Hannah, and one knows how she feels.

Richard Bean's new comedy, England People Very Nice, has a far more epic sweep and bags of boisterous humour, charting more than three centuries of immigration, racism and assimilation in Bethnal Green, east London. Nicholas Hytner's multi-ethnic cast plays rolling generations of East End citizens: persecuted French Huguenots, famine-stricken Irish, Jews, Indians, Pakistanis, Somalis ....

On occasions, this lapses into a strip cartoon, accompanied by tiresomely Pythonesque projected graphics. Still, it's hard to resist the rough-and-ready brio, the running gags of Sophie Stanton's effing-and-blinding cockney landlady or the interracial love repeatedly breaking out between the impish Michelle Terry and indefatigable Sacha Dhawan.

Bean and Hytner also become more satirical and alarmed as they career into the 21st century and come face to face with rekindled xenophobia and teenage Muslim fundamentalists who shout "whore" at local women, born and bred within the sound of Bow Bells. There are territorial battles everywhere you look.

'Three Days of Rain' (0844 412 4658) to 9 May; 'The Stone' (020-7565 5000) to 28 Feb; 'England People Very Nice' (020-7452 3000) to 30 Apr