Flare Path, Theatre Royal Haymarket, London <br/> In a Forest Dark and Deep, Vaudeville, London<br/> Ecstasy, Hampstead,London

Celebrity casting doesn't suit Trevor Nunn's Rattigan period piece, but Mike Leigh's superb 'self-revival' is Chekov in a bedsit

If this opener is anything to go by, the Haymarket is on a winning streak under Trevor Nunn's new artistic directorship. The venue aims to shine as a top-calibre West End playhouse with a stand-out policy: appointing a big-name AD every year to programme seasons.

Admittedly, Nunn's staging of Flare Path is a slow burn. Terence Rattigan's Second World War drama isn't immediately heartbreaking, when an RAF pilot's actress-wife plans to leave him for a matinee idol. The rakishly handsome screen star, Peter (James Purefoy), checks into a Lincolnshire hotel where Patricia (Sienna Miller) is staying, near her pukka husband Teddy's aerodrome. Teddy and crew fetch up – unaware of Patricia's adultery – believing they have one night free to party with their spouses. In the hotel'soak-panelled lounge, the 1940s lingo occasionally seems, I say, darling, awfully sorry, but ever so slightly wooden. Maybe the celebrity casting of Miller is the snag. Some of her lines sound more superficially delivered than felt. You might also think Rattigan's lower-class characters are only there to serve as droll caricatures.

Yet the piece deepens in due course. After Teddy's squadron leader (Clive Wood) tells them they must head off on an exceptionally dangerous raid, it's hard to not sob out loud. Rattigan's skill lay in gradually exposing the emotional layers beneath the chipper front of old-fashioned Brits.

A star-in-the-making, Harry Hadden-Paton is shatteringly poignant as Teddy, when he can't sustain the stiff upper lip any longer. While refusing to renege on his duties, he confesses his nerves are shot to hell, crying like a terrified child in his wife's arms.

Sheridan Smith (who has just won an Olivier for Legally Blonde) proves she can steer between larkiness and pathos too. As Doris, a barmaid who has married an ex-pat Polish officer, she switches from comic perky chatter to near-mute grief when he's missing in action. She conveys the unwitting pain of others' comments, just sitting in an armchair, trying to maintain a brave face as their lives carry on around her.

Rattigan clearly saw the problems, within personal relationships, caused by repressed emotions. But in Flare Path he was manifestly for the war effort too. Ultimately, the play appreciates both those who open up and those who stay tight-lipped because they believe that, in calamitous times, there are greater horrors to combat than individual unhappiness.

That moral lesson feels startlingly timely. Especially so in a week when our everyday concerns were put to shame by the stoicism in Japan. So, another Rattigan centenary revival proves touching and astute. As for the Haymarket, one cuckoo does not, of course, make a summer. Bear in mind Nunn's 2010 West End clanger, Birdsong. But Flare Path is definitely worth seeing.

In a Forest Dark and Deep, alas, is not. Olivia Willams and Matthew Fox (from Lost) are both seriously good actors, playing out the American writer-director Neil LaBute's predictably nasty sibling reunion. (He is interviewed with the producer, in this week's New Review, page 54.)

Betty, who has become a college dean, has asked her possibly psychotic, redneck brother to help her clear out a log cabin in the woods, in the middle of the night. She says, casually, that her husband has been renting it out to a guy, some student, who's vamoosed – maybe because his mum has cancer or something. Bobby is irked and twitchily spoiling for a fight, harping on about her promiscuous adolescence.

There's obviously a skeleton in the cupboard. Apart from the moments where Fox's bearded Bobby suddenly looks like a sternly moral then merciful Christian God, LaBute's revelations offer few surprises. The tissue of lies is transparent, and his Sam Shepard-meets-Gothic horror format seems hackneyed, complete with lightning and guttering lamps.

Not that much happens, dramatically, in Mike Leigh's early slice-of-life play, Ecstasy. Yet his self-directed Hampstead Theatre revival is superb. A poky, grey Kilburn flat floats in a sea of darkness. A passing police siren wails. Dogs bark. Sian Brooke's Jean, a lonely soul, knocks back double gins and exudes unspoken despair – rubbing her shin by an electric fire.

In the opening scenes, we see her stuck in a cold, abusive affair. Then, however, Ecstasy drifts into a knowingly protracted and exceptionally subtle portrait of blue-collar camaraderie. Jean's old Brummie friend, Dawn (Sinead Matthews), comes round with her Irish builder-husband, Mick (Allen Leech), and the dull but gentle Len (Craig Parkinson). He once courted Jean. They get plastered, blather nostalgically and have a singsong.

The ensemble naturalism is flawless, like Chekhov in a bedsit. The comedy is wonderful, especially from Matthews' squawky Dawn. And after Parkinson and Leech's priceless rendition of Elvis's "Heartbreak Hotel", Jean's folk-singing is an extraordinary still point: an expression of radical melancholy and tentative hope, suddenly reaching way beyond this snapshot of 1979's winter of discontent.

'Flare Path' (0845 481 1870) to 4 Jun; 'In a Forest Dark and Deep' (0844 412 4663) to 4 Jun; 'Ecstasy' (020-7722 9301) to 9 Apr

Next Week

Kate Bassett hopes to be blown away by The Umbrellas of Cherbourg

Theatre choice

Set in a London comprehensive, Mogadishu, right, is an outstanding first play by a teacher-turned-writer. Playing at the Lyric, Hammersmith (to 2 April), it explores the role of a gang's lies in the dismissal of a hitherto liberal teacher. At the BAC in Battersea (to 9 April), Kneehigh revive their award-winning, early hit The Red Shoes.