There is a clever conceit underlying Douglas Maxwell’s sparky romantic comedy. It imagines the possibility of a sexually charged relationship being sustained without physical contact. Played out on stage, this improbable idea hits home on two levels.

Meeting at a 21st birthday party in 1995, two students – one law, one media studies – agree to maintain the erotic anticipation of their first encounter by never touching each other. If they ever do, the relationship will be over.

We see them then and now, played by two sets of actors. The man, Robin Chilton, is true to their deal and goes from gawky by nature (Alexander Tait) to ascetic by choice (Sandy Grierson). The emotionally repressed student we meet at the start becomes a chief sheriff officer, ruling the law courts with a pedantic attention to detail – and living entirely for work.

Meanwhile, the woman, Iris Rossi, forgets all about their arrangement and goes from a formidably spontaneous drop-out (Sophie Fortune) to an endearingly chaotic art writer (Adura Onashile). Thanks to her wayward involvement with a paint-throwing climate campaign, she bumps into the fiftysomething Robin in the sheriff court.

On one level, the no-touch rule allows Maxwell to ask philosophical questions about human behaviour. Might deferred gratification be better than wilful abandon? Is self-denial a safer option than surrendering to instinct? Or are the mistakes what life is all about? As Iris says, without experience you can have no wisdom.

Then, on the physical level, the conceit introduces a theatrical game. In Sally Reid’s excellently acted production, with Vicki Manderson as movement director, the actors weave around Jessica Worrall’s elegant set with cat-and-mouse precision, coming within a whisker of each other but never touching. That is, of course, until they inevitably do, the play’s big question gets an irrefutable answer and our hearts swell.

Writing with a keen sense of narrative structure, Maxwell wittily dramatises the generational divide, as Tait and Fortune play a succession of young characters trying, and generally failing, to keep the grownups on track. It is funny, moving and messily human.