Two volatile siblings get stuck in a cabin during a storm, not realizing they are actually in play by Neil LaBute.

They’re holed up in a cabin in the woods and a violent thunderstorm keeps knocking out the lights, but the biggest problem facing dangerously volatile siblings Betty and Bobby is that they don’t know they’re in a play by Neil LaBute. If they did, like most of the audience they would wise up to the play’s too obvious twist a helluva lot faster. As much as Matthew Fox and Olivia Williams impressively paw the stage and claw one another, “In A Forest Dark and Deep” is so in hock to its contrived plot that attempts at depth are doomed.

Thirtysomething Betty (Williams) is a successful, married, literary academic who is head of her department. Somewhat hurriedly closing up her isolated country home – Soutra Gilmour’s comfortable A-frame house set – she has dragged her resentful, Nirvana-T-shirt-wearing carpenter brother Bobby over to help her pack in order to make way for a renting couple.

You don’t have to have a PhD in LaBute studies to be suspicious when, about 60 seconds into the action, Bobby quotes, supposedly off-handedly, “The truth hurts.” Betty says she’s never heard the expression before, he accuses her of lying, she denies the charge but, a few lines later, tells him she was kidding. The following 104 minutes consists of peeling back layers of lies.

Their increasingly fiercely flung accusations and recriminations over long-held grudges about past behavior and present attitudes is a bit like Albee without the alcohol. But what really gives this a second-hand feel is the way in which LaBute seems to be channeling Sam Shepard, a crossing “True West and, with its hint of incest, “Fool For Love.”

In the typically caustic slanging matches, the easeful, rangy Fox in particular ratchets up emotion by allowing anger to erupt from beneath an eerily calm surface. Williams returns serve with equal flair but has an unenviably hard task.

Playing a character who, it is quickly revealed, is lying all the time, she is faced with a dilemma. If she shows Betty lying too obviously, she weakens both her character and the tension. Do it too well, and Fox’s character looks absurdly smart. Helmer LaBute allows her to fluctuate, which does his text few favors. She also struggles beneath the overriding problem that once you realize someone is constantly lying, it’s hard to take what they say seriously. And LaBute has things he wants to get off his chest.

Towards the end of this self-consciously gothic, would-be thriller, what actually happened emerges via clunky plot revelations and they start arguing about personal responsibility and morality, warped and otherwise. Bobby, unexpectedly, is more than a little puritanical. But with everything tethered to horror-style reversals of the “truth,” their debates never lift into drama.

The scintillating savagery of early LaBute plays has atrophied into cliche. In “The Shape of Things,” the manipulations of the dialogue superbly embodied the playwright’s wider themes. Here Bobby’s foul-mouthed fusillades at the expense of women and, to a degree, gays, are supposedly excused because they’re shot down by Betty. What’s wearying is that they land with the tired sense of expectations being met rather than the rush of new ideas being audaciously explored.

In a Forest Dark and Deep

Vaudeville Theater, London; 685 seats; £45 top

• Production:An Anna Waterhouse, Nica Burns, Max Weitzenhoffer, Jay Harris, Josephine Genetay, Charles Diamond presentation of a play in one act written and directed by Neil LaBute.
• Crew:Set and costumes, Soutra Gilmour; lighting, Mark Henderson; sound, Fergus O'Hare; production stage manager, Sheena Linden. Opened, reviewed Mar. 14, 2011. Running time: 105 MIN.
• Cast:Bobby - Matthew Fox Betty - Olivia Williams