First Night: In A Forest, Dark and Deep, Vaudeville Theatre, London

The star of Lost is one of two winners. Pity about LaBute's input...

Neil LaBute's last play in the West End was called Fat Pig. By the end of In a Forest, Dark and Deep, you could be forgiven for thinking the drama should be subtitled Slender Cow.

An intermittently taut two-hander, it receives its English premiere in a production by the author that stars Matthew Fox (famed for TV's Lost) and the redoubtable Olivia Williams.

They both give scorching performances that are, to my mind, a distinct cut above the material. The play unfolds as a cross between a psychological thriller and a slug-fest of incestuously tinged sibling rivalry. It's as though Fool for Love, the bruisingly eroticised brother-and-sister play by Sam Shepard, had been retooled according to the precepts of LaBute's great mentor, David Mamet.

Betty, an academic and college dean, urgently needs to clear out all of the paraphernalia of the last, hurriedly departed person who rented the lakeside cabin which she and her husband own as a holiday home.

Since her spouse is otherwise engaged, she summons her brother Bobby, who is blue-collar beefcake to her blue-jeans bluestocking.

Almost immediately you smell a rat, because if Betty's principal aim was really to pack up books, she might as well have glued the volumes to the shelves as recruit the help of a brother with whom she is locked in a long history of sparring intimacy.

No sooner is he through the door, trailing a six pack of beer, than Bobby is taunting her with her sexual past and decrying her chosen literary life as a prissy, undeserved cover-up. Matthew Fox is superb at conveying the character's edgy intensity and simmering violence and at arousing mixed feelings in the audience.

Bobby has some blackly hilarious moments of political incorrectness. At one point, he brings up a woman he has seen on the news whose husband, a veteran of the Iraq war, has been rendered impotent and incontinent. "She's gotta be sick of sitting on top by now, right?" says Bobby, who ludicrously argues that his restraint in not trying to come between the pair is an index of his moral probity. And yet, as Fox's subtly shaded performance indicates, there is a sense in which the brother's near-misogynist resentment at Betty's sexual history is a token of his loving (albeit semi-incestuous) concern for her. Olivia Williams has the more difficult task as the initially mettlesome and increasingly distraught sister.

If the Pinter universe largely boils down to a division between the bullies and the bullied, the population of Planet LaBute is segregated into pens marked "manipulators" and "manipulated". For reasons that it would be unfair to disclose, Betty is both.

But where you feel the author knows Bobby from the inside, Betty proves to be just a clutch of clichés about the ageing female beauty that wind up seeming as embarrassing as the schlock thunder-and-lightning that cause convenient power cuts in the A-frame cabin, without generating any bona fide tension.

This forest is dark, but it is not all that deep.