The Mentalists, Wyndham's Theatre

A Richard Bean play is always to be welcomed – he wrote England People Very Nice and One Man, Two Guvnors, two of the most enjoyably rambunctious comedies of recent years – but also with a note of caution. Sometimes, as with The Big Fellah, there's more style than substance (or more jokes than narrative) and that's the case with his 2002 play The Mentalists, being given a West End revival with a huge comedy star making his stage debut.

We are in a dingy north London hotel room (nicely realised by Richard Kent), where Ted (Stephen Merchant, co-creator with Ricky Gervais of The Office and Extras) reveals his plan to create a utopian community based on the philosophy of the controversial behavioural psychologist BF Skinner (regarded as the anti-Freud). Ted is being helped by his best mate, Morrie (Steffan Rhodri), who's there to record Ted's call-out for people to join him in this new community. Morrie normally uses his camcorder to make low-rent porno films, which incidentally often involve balloons – a line from the first act that supplies a brief but very funny sight gag in the second.

There's limited character development in this brief study of loyalty between friends and self-delusion

Ted and Morrie are old friends and yet appear to know very little about each other's current lives. Morrie is a slightly camp Soho hairdresser with an endless succession of much younger girlfriends who spouts increasingly obvious inventions about his life, while Ted is a fleet manager for a cleaning services company in Swindon, who flies off the handle very easily. For Daily Mail-reading Ted, Skinner's 1948 novel Walden Two is his Book of Revelations, and a work about which he has only the slightest comprehension. What matters to him is that it appears to be about order.

This being a Richard Bean comedy, there are many cracking lines, delivered with relish by Rhodri and Merchant; the Greeks peaked early, Ted says, what with their geometry and mathematics, while he didn't advertise in the Guardian for people to join his community because “I didn't want Guardian readers fucking it up for everybody else”. Morrie's fictions, meanwhile, get better as the play progresses; his “dear old dad” was the only Briton who boxed at every weight (“it's all about chips”), and he knew Bill Gates when he sold sandwiches down the Seven Sisters Road. 

Bean cleverly deflects any questions we may have about Ted's mental state by making Morrie the more obvious fantasist, and he reveals how the two men know each other only very late in the play. But there's limited character development in this brief study (110 minutes with an interval) of loyalty between friends and self-delusion.

Rhodri sympathetically portrays a man who lies with ease but who has, however, a keen sense of reality about those he loves. And, while Merchant is a plausible and engaging misfit, his transformation into borderline psychotic takes some believing in Abbey Wright's straightforward production.

• The Mentalists is at Wyndham's Theatre until 26 September