"I still believe that the best plays are about people," said Terrence Rattigan, "not about things." The reason, perhaps, why Rattigan work was for so long out of fashion, overshadowed first by the kitchen tap of the 60s and more recently by the faceless threat of post-9-11 terrorism.

But if ETT's revival last year of French Without Tears showed Rattigan's ease with comic interaction, Edward Hall's current production of The Deep Blue Sea shows him as a student of human nature at its truest level.

The play is necessarily a grower. Despite opening with the attempted suicide of its heroine, Hester Collyer, the first act develops slowly, as we learn of the context - that Hester has left a comfortable life with her High Court Judge husband to move in with a handsome but alcoholic ex-RAF Pilot, an affair that has quickly lost its fire.

At first, the post-war morals distance us from empathising. But as we learn more, we realise that this is a timeless tale of a women desperately and hopefuly in love with a man who can't return her feelings.

Scacchi puts everything she owns into the part - and her realistic portrayal of an upper-class woman makes her desperation at her lover's feet - "Don't leave me, Freddie, don't leave" - even more shocking when it comes.

Simon Williams as her husband Sir Willian is stiff-upper lip personified, but with a kindness and tenderness that truely moved. And there is great support from Jacqueline Tong as her Ladbroke Road landlady, and Geoff Breton and Rebecca O Mara as the goung married coupl across the hall.

The only weak link is Dugald Bruce Lockhart's Freddie, who is too much caricature to make Hester's feelings for him understandable. Then again, our love for another person is never rational, nor is our response if that pereson cannot love us back.

"When you're caught between the devil and the deep blue sea, the deep blue sea begins to feel rather inviting," says Hester, and Francis O'Connor's set plays on this conceit to great affect. On the surface, it's a typically London room-to-rent, with high ceilings, tiny kitchen and shabby fittings and furniture. But the gauzey back wall ingeniously reveals the staircase outside and, submerged in blue light at the end of the first act, suggests that Hester is slowly drowning in her own existence.

The superb third act brings philosophy into the room as Scacchi is forced to discuss her situation with two neighbours, the naive and idealistic Philip Welch (Breton) and then with the enigmatic and world-weary Dr Miller, cleverly portrayed by Tim McMullan..

But the reality of pain hits home in the last scene as Hester finally taking Miller's advice - to find something to live for within herself. Somehow the final quiet image of a women packing her lover's clothes into a suitcase is a hundred times more powerful than the sight of her prostrate body at the start of the play.