Standup is performance in extremis, self-projection in the raw – and has long appealed to dramatists interested in the faces we present to and conceal from one another. That seems to be the territory of I’m Not Being Funny, too, as we meet two young parents prepping in their living room for a forthcoming open mic night. Peter wants to tell corny jokes; Billie wants to tell stories about her – well, their lives. An interrogation looms into the uses and abuses of onstage humour, but that is not, in the end, what we get.

I’m not convinced that Piers Black’s play quite marries how it starts with what it becomes. There is something off about the pair practising comedy together. Are they planning solo slots – the classic “tight five”, as Peter refers to it? (He frets he only has a “loose two”.) Or are they workshopping a double act? That question feels more pertinent when, after a few flashbacks hinting at a dramatic backstory, the play swerves into more traumatic territory.

Under Bryony Shanahan’s sensitive direction, and with contributions from toddler Ruby via a baby monitor, the stars Jerome Yates and Tia Bannon handle the tonal shifts with grace, as adept at delivering Black’s rookie standup material as they are nursing one another’s emotional wounds. The relationship is compellingly drawn, as Billie urges her husband to confront in comedy what he’s hiding from in real life. The pain, when it comes, is deftly undercut with humour (see the droll hospital elevator anecdote), and there is endearing 90s nostalgia as the duo recall their teenage meet-cute.

But the longer it goes on, the further the play drifts from its trainee-comedian conceit – notwithstanding the revelation of why these fraught parents are giving standup a go, which feels contrived. We’re certainly a long way from tight-fives at the end of these 90 minutes, which richly deliver on the play’s title and feel emotionally overwrought. You’re left with a play that engages only so far with its questions about humour as a defence against, or triumph over, tragedy, while taking us deep into the hearts of a couple staring the worst possible outcomes in the face.