To say that David Lewis' therapeutic new play has issues is rather to understate the point - the chorus of nut-jobs and loonies at the heart of this love-hexagon turn the Orange Tree into a kind of incestuous Bedlam.

There is certainly method in the madness, mind you. Simon Mattacks is brilliant as 'twitcher' Terry, giving a deliciously composed performance as a man whose quest to see new birds has forced his marriage into the counselling room. [Paul Kemp] is equally impressive as shrink Charlie, whose pugnacious attempts to save other people's marriages only serve to jeopardise his own.

Lewis' direction is the equal of his script. When the characters recount episodes to their therapists, the action is briskly re-staged to show how they remember it, which is often subtly and comically at odds to how it actually was. And the careful handling of exits and entrances neatly shifts the action around the floor (important given the in-the-round staging) without ever seeming contrived.

The writing gets stronger as the characters flail. Fran's observation that some people can "only love from a distance" is a lovely compression of one of the play's guiding motifs. One of Charlie's rants - on the cyclical nature of male/female relations - is a joy. And underpinning the script is a wry awareness of its own tricks, lending it a satirical rather than ostentatious flavour.

The closing stages of the play are a chaos of mental and sexual capitulation. Just about everyone gets made a cuckold of, and just about everyone reaches the end of their tether. And yet despite the lunacy and betrayal there is a gentleness and humour to the finale which is in keeping with what has come before.

Seven Year Twitch won't alter your mind, but it will certainly tickle it.

- Ben Aitken