'It’s a bit like being at the controls of a jumbo jet after four pints at lunchtime. It’s exhilarating but terrifying.’ Douglas Maxwell is employing a typically vivid metaphor for entering into fatherhood. With a child of three months recently arriving chez Maxwell, it might well be the time for this frequent commentator on themes of childhood and adolescence to return to familiar ground.

Maxwell’s new play, brought from Birmingham Rep to his Scottish home territory, returns to a familiar emotional heartland in mapping the journey from boy to man (his adolescents are seldom female). This rite of passage is alluded to in a succession of his most warmly received plays, from Our Bad Magnet, through Decky Does a Bronco and on to Helmet. His new piece focuses on a young man who is suddenly confronted with the disappearance of his kid brother, who was disabled after a near-drowning in early childhood.

Maxwell takes up the story: ‘Elliot, the central character knows how cruel other kids can be, so rather than being seen as less than human, he tells his brother that he’s not human at all, that while he was underwater, some aliens swapped him, and that he has special powers.’

This tall tale takes on the status of myth, with Elliot convincing his brother that he’ll be picked up by the mother ship later. Maxwell continues: ‘Time passes, and the disabled brother leaves a message with their stepmother saying the mother ship is coming back. He then disappears.’ Add to the ensuing search a pregnant stepmother, her partner and a dysfunctional policeman, and you have a recipe for a winning comedy.

Yet, the audience Maxwell’s play is facing can be demanding. Birmingham Rep commissioned this play as a story that would tour schools. Does he have trepidations about this group? ‘Well, it’s not a play that’s just for teenagers. I’m thinking of it as being like a “PG” or a “12” in films; it’s a play for everyone, but teenagers can come along’, he says. ‘All the same, I was attracted to it, because it’s a no bullshit audience. If they don’t like it, that audience will shout out: “This is rubbish.” If they’re not enjoying it, they’ll fidget, put the mobile on, and so on. It’s not like an older audience, where if they’re not liking it, they’ll sit quietly and think about sex, or wish they were at home watching The Sopranos. A teenage audience will expect to be entertained from the kick-off, and they’ll let you know if they don’t like it.’

But what is it about Maxwell’s work that brings him back again and again to the formative years of young adults? ‘I think most writers have their own piece of turf that they consider their own, and go back to. With great writers, this can be a whole field – in my case I’ve got a little tiny piece of real estate that I call my own. You don’t want to be there all your life, very often you go away from it. In my case I’ve written a lot of other work that’s gone away from it, but it’s so nice to come back.’

Traverse Theatre, Edinburgh, Tue 25–Sat 29 Mar.