A likeable man with donkey ears appears on the stage. It’s Nick Bottom from A Midsummer Night’s Dream, here to perform the celebrated play within a play, but there’s a problem: the rest of the cast haven’t turned up. The show must go on of course, so Bottom scraps the script and launches into a kind of stand-up routine. Yet as time goes on and his rapport with the audience grows, he begins to speak more candidly than he’d originally intended to.

At first, actor Charlie Day plays Bottom as a showman, confident in his own celebrity and geeing up the crowd to cheer him on. But there’s a vulnerability just below the surface – showing through each time he explains a joke, or apologises for a piece of audience interaction which (he suddenly worries) he took too far. His neediness, for me, stays just the right side of being grating; and while the humour of this opening half is very gentle, Day’s a charismatic man and it’s genuinely funny.

You can tell, though, that there’s something else to come, and when the transition arrives it’s both sudden and convincing. Now we’re watching Bottom crumple on stage, the loveable figure we’ve just got to know sinking into a swamp of uncertainty and self-doubt. It’s hard to watch from someone we’ve come to like and, for the 99.9% of us who’ve at some point in our lives felt the same way, it’s also wretchedly familiar.

What lends the show its poignancy – and a frisson of discomfort at times – is the unspoken parallel between the world of the play and what’s happening in real life. Yes, Charlie Day is playing a role and yes, unlike Bottom, he’s had time to rehearse. But he really is an actor, he really does crave approval as all actors do, and he really does look terribly exposed up there on the stage. So when Bottom begins his spiral into sadness and self-loathing, it feels hauntingly possible that those emotions are real.

It must be said that the set-up doesn’t make total sense. This is meant to be Nick Bottom from the world of Titania and Oberon, yet he seems to live in London and to hang out with William Shakespeare. And it’s hard to reconcile the self-aware figure we see on the stage with the character we know from the Bardic text. The donkey ears did their job of getting my attention – but as a hook to hang the show off, they’re really rather flimsy.

But in a sense that doesn’t matter, because Bottom is only a cipher here: a surrogate for anyone who feels they’re faking it, in any aspect of their life. If Bottom – or is it Day? – can summon the courage to voice his self-doubts, then perhaps we all can too. In a world where so many people are faking a smile, that’s an important message to share. And yet – it’s all wrapped up in an endearing and entertaining package, delivered with heart and conviction.