The success of Tony-winning London hit “One Man, Two Guvnors” has made Richard Bean a bankable playwright: His factory-set 1999 debut “Toast” popped up on the London fringe last year and now “The Mentalists,” a slight, subtle two-hander that was originally part of an experimental National Theater season in 2002, has been repurposed as a star vehicle for Stephen Merchant, co-creator of “The Office” and “Hello Ladies,” to make his West End debut. It’s a mismatch, though, and Abbey Wright’s production steamrolls the play’s ideas with sitcom-style laughter — and can’t even find too much of that.

Merchant plays Ted, a middling man in the middle of a mid-life crisis, convinced that he’s hit upon a path to enlightenment. Inspired by the psychologist B. F. Skinner’s sci-fi novel “Walden Two,” which sets out a blueprint for a utopian community, he’s come to a tatty hotel in Finsbury Park to record a video message to like-minded souls. Behind the camera is his old ‘china’ (rhyming slang for ‘mate’) Morrie, a camp cockney hairdresser and part-time soft-porn producer, played by Steffan Rhodri (“Gavin & Stacey”).

Bean’s play is far more interesting than Wright’s production allows. Here it becomes an odd-couple comedy about two eccentrics left to their own devices to extemporize at length. Ted is a small-town grumbler, a discontented conservative huffing and puffing about the way things are heading. Morrie’s a fantasist, muttering fabrications about his father (“He invented the miniskirt, my dad”) and various virtuosic sexual conquests, among them artists and aviators.

Bean used to be a stand-up comedian and he’s given his characters half-decent routines, which Merchant and Rhodri dispatch as such. Nerdy Merchant rattles off a list of Britain’s motorways and fumes about the fake maple wood door. Rhodri shuffles around and soothes his old friend with a relaxing head massage.

What Wright doesn’t tap into, at least not until the very end, is the play’s concern with mental illness. Merchant and Rhodri play the surface without digging deeper, and there’s no sense of the history between these men — no sign of their 15 years in a children’s home together, no trace of their previous misdemeanors. Their behavior never swerves into strangeness or flickers with darkness. While Wright’s right to keep us in the dark about their mental health issues, she never makes anything of the ambiguity Bean sows. Both men seem like ordinary oddballs. That Ted’s just killed “a wino” and has the corpse in his car boot doesn’t make you re-evaluate the man. Instead it tips the play past credibility.

It shouldn’t. Bean’s up to something more sophisticated — arguably more sophisticated than he can handle. Invoking Skinner throughout, the play illustrates and critiques his psychological theories, in particular that external behavior can be evaluated but not internal thoughts. Ted and Morrie might act in an outwardly rational manner — quirky, but not insane — but both are delusional and mentally ill. You see that clearly at the end, with Merchant curled up on the bed, Rhodri stroking his hair and a squad of armed police outside the door, but it comes as a bolt from the blue rather than shedding new light on everything that’s come before. Merchant never finds the desperation in Ted. He seems a hare-brained bumpkin rather than a man on the edge.

Skinner also believed that our behavior tends towards replicating itself, a process known as reinforcement — hence Morrie’s trotting out the same stories over and over, and Ted’s fretting about the changing world. It’s a play that sees the reasoning in right-wing thinking, admitting that the Daily Mail and conservatism might have their place, psychologically speaking, while also suggesting a certain irrationality, even a madness, in that. Not that you’d know it from Wright’s production.

West End Review: ‘The Mentalists’ Starring Stephen Merchant

Wyndhams Theatre; 759 seats; £59.50 ($92.73) top. Opened, reviewed July 13, 2015. Running time: <strong>1 HOUR, 50 MIN.</strong>

  • Production: An Old Vic Productions, Smith & Brant Theatricals, Steven Harris and Sam Levy production of a play in two acts by Richard Bean.
  • Crew: Directed by Abbey Wright. Design, Richard Kent; lighting, David Plater; sound, Ben and Max Ringham.
  • Cast: Stephen Merchant, Steffan Rhodri.
  • Music By: