Edgy, schematic, brilliantly constructed, unpredictable: you couldn’t ask much more of a two-hander: but Neil LaBute’s In a Forest, Dark and Deep, a world premiere, is only a sibling stand-off companion piece to his much richer, and more disturbing, In a Dark Dark House at the Almeida three years ago.

This new play’s efficiently and engagingly performed by hunky Lost star Matthew Fox and elegant, gestural Olivia Williams as the carpenter Bobby and the college lecturer Betty, but they don’t really want to sleep with each other enough – this is a comment on the characters as well as the acting – and, after one hour, fifty minutes, you don’t mind all that much about parting company with them.

The activating discussion point is Betty’s promiscuous past, her failing marriage and her recent infatuation with a student on the campus where she teaches. She’s called round Bobby, who sports a Nirvana T-shirt, to help clear out the lakeside retreat she’s been renting out, and there’s stuff that needs dealing with.

The main stuff, of course, is their own sibling relationship, which is barbed with resentment, obsession and envy. There’s also a cultural divide: Bobby has less respect for novelists than he does for blokes who can clear out sceptic tanks. His sister is therefore some sort of enemy; but this position is as absurd as her own casuistic posturing.

LaBute skilfully weaves his way through his own arbitrary revelations: that Bobby was a violent husband in two marriages, and that Betty slept around with his mates. Lurking back somewhere there is their father. On the sofa, in a rare moment of repose, they share a joint and get closer.

But there’s a cover-up to be sorted, and the play moves on stealthily through thunder and lightning, knowing exchanges about the relative merits of U2 and Pearl Jam, and some good, unsettling gags that test our liberal, knee-jerk responses to issues of colour and sexuality.

I’ve always liked the way LaBute messes with PC tolerance, but it’s quite an easy trope if you’re looking for controversy in the theatre. We may be coming through a post-Clybourne Park era where this kind of writing doesn’t look quite as daring as it once did. But it’s good to have LaBute back in the West End, mixing it all up a bit.