There could not be a better moment for this novel. Doctor Who has never been bigger, and a whole new generation has just experienced the phenomenon of regeneration, where one Doctor changes into another. When David Tennant made way for Matt Smith in the role, the last words he cried out echoed the feelings of millions of fans: "I don't want to go!"

The genius of Paul Magrs's book is the way it uses this notion of regeneration as a metaphor for adolescence: a time when your whole life changes, a new body grows around you, and you have no idea who you may be becoming  just that all familiar certainties are gone for ever.

The story is set in 1981, when Tom Baker gave way to Peter Davison (below) as the Doctor. Its protagonist is an obsessive fan called David who is on the verge of becoming a teenager, and is terrified at the prospect. He's happy with his childhood in working-class north-east England, and doesn't want anything to change. He takes comfort in the weekly ritual of watching Doctor Who (or The Show, as true fans call it). He and his best friend, Robert, have always shared their love for The Show, but now Robert seems more interested in chasing girls, listening to goth music and, most threatening of all, dismissing The Show as childish rubbish.

Magrs's take on early adolescence is very sharp and beautifully nuanced. Almost every page contains some seemingly offhand observation that rings true, from the cringing embarrassment of boys' changing rooms to the way the tiniest details of popular culture can become matters of life or death, fiercely personal and political.

This is backed up by a fully realised pop-cultural landscape that encompasses not only television but music, books, comics . . . even chocolate bars. It might be wondered whether all this period detail would mean anything to a teenager today  but it isn't retro reference-dropping for its own sake. Rather, Magrs treats the details as if writing a historical novel or science fiction: using them to build a picture of a world, and show what matters to the people in it. The reader may or may not know the distinction between "Laughing Gnome" David Bowie and "Ziggy Stardust" or "experimental Berlin" David Bowie  but will surely recognise the crushing humiliation of being seen to like the wrong things, of being less cool than the people around you appear to be.

There is sexual politics, too, as David comes to realise that he is gay, or at least not attracted to girls. There are some similarities here with Jacqueline Wilson's standard-setting Kiss, as well as with Magrs's own Strange Boy. But in this respect, the book seems more preoccupied with what David is not than with what he is, and perhaps thereby misses opportunities for narrative development.

It should also be said that although the writing is deeply thoughtful and textured, it's not exactly action-packed. There are plot strands that go nowhere, and an epistolary section that is essentially a collection of sketches. Yet the emotional dynamics keep it moving towards a conclusion that is both uplifting and convincing.

The discovery that there are people in the world whom David might hope to become  people who have not lost everything that made childhood magical, while confidently inhabiting the new bodies and aspirations of adulthood  is something anyone can take heart from, whatever their situation. And this sense that change may be survivable after all makes this not just a book for Doctor Who addicts, but for everyone interested in the transformations that come with growing up.

SF Said's Varjak Paw books are published by Corgi.