Many years ago, I went to a vast furniture trade fair in Chicago. At five indoor acres, it dwarfed anything we had in Europe and in the most lavish stand of the largest American manufacturer, Steelcase, there was an expensively made movie with a set featuring their latest model desks put on wheels so Steve Martin could scoot about on them and sing a joky song about wipe-clean plastic laminate and soft-close drawer runners. It was cheesy, arch and toe-curlingly unfunny. It was also the first time I’d been exposed to Mr Martin’s specific talents and I asked my designated salesman if, in the United States, they’d call him an actor, or a comedian. ‘We surely would call him a comedian’ he countered brimming with Mormon enthusiasm for his product and its highly-paid spokesmodel, ‘what would you call him in Britain?’

‘In Britain,‘ I sighed, ‘we’d call him a cunt.’

In a similar way, the wit and charm of US comedian Wallace Shawn is lost on me. I never saw him as Alicia Silverstone’s teacher in Clueless and haven’t caught whatever comedy series made him popular, on a channel I’d have to pay Murdoch to see. No matter, I doubt he’d laugh at my stuff either, but as he’s here in his own play at the National, I was willing to give it a go.

Evening at the Talk House starts with a 17-minute monologue recited by Josh Hamilton as a stalled playwright but dressed as a geography teacher, and goes downhill from there. It’s about the reunion of a group of actors from a long-discounted TV show, in a shabbily forgotten drinking club, location unspecific since it’s an Anglo-American cast using their own accents. Set also in that abused cliché a ‘dystopian’ future where theatre has died as an art form, some of the ex-practitioners have enrolled instead in a government-sponsored programme of identifying and killing undesirables, fusing The Good Companions with The Hunger Games.

Of course it’s metaphorical and Shawn has points to score about how easy it could be for people to sign up to state-sponsored vigilantism – glancingly topical in the post-Paris collective outrage. But despite Ian Rickson’s urgent direction, it’s all too muddied and opaque and as the actors babble about shows they were in and bitch about people they once knew it actually feels more about being alienated from a group to which you never really wanted to belong.  Which is more or less what’s happened to Shawn’s own character, a dishevelled hasbeen who has been randomly beaten up by people he claims as friends.

Go to this, and you’ll know how he felt.

It’s too earnest for its own good – if you’ve got ideas like this to sell, you have to make the medium more palatable. Best you can say is that the set could be re-used for The Mousetrap. What the ideas can be re-used for is harder to tell.