As Gregor Samsa awoke one morning from uneasy dreams, he found himself transformed in his bed into a gigantic insect. That much, of course, everybody knows; but Kafka’s famous work still rewards further study. As we file into the theatre, though, we find that the cast of sixth-formers from Guildford High School are studying us. They’re asking questions, gathering data, taking votes on what it means to be “normal”.

It’s sensitively done – everyone can see that the “secrets” we’ve been handed are as fictional as Metamorphosis itself – but it’s a powerful inversion of the usual theatrical order, echoing the sudden change that begins Kafka’s tale. The theme of “normality” runs through the piece, underlining how the Samsas’ adherence to convention adds to their intolerance of a brother and son. In an inspired motif, their oppressive apartment is crowded with duplicates; there are two Fathers, two Mothers, and two sister Gretes. Yet Gregor remains largely unseen, pushed gradually aside by those who once loved him.

The physical performance is impeccably choreographed and remarkably assured. Bright blue photo frames make for striking and versatile props: they can frame the action, form the pages of a book, close around a person’s head like a claustrophobic cell. Every move’s intentional and perfectly placed, throwing attention fluidly from one actor to another and building up the detail of Gregor’s shrinking world. There’s humour there, too – look out for the thickset wardrobe as it clumps around the stage.

While half the cast form the frame-wielding chorus, the others slip deftly between a multitude of characters. I particularly enjoyed Harriet Moody as The Chief Clerk Himself, whose jumped-up self-importance matched the production’s grotesque tone without slipping into overt parody. Maia Greaves excels too as The Woman In The Picture, pairing an operatic singing voice with some gloriously goofy faces. She often speaks for Gregor when he can’t speak for himself, and she commands the space without stealing it.

Though the tone’s often light, they find emotional depth when it’s called for: Malena Tolentino is haunting in one crucial scene, voicing Gregor’s wistful anguish as he hears his beloved sister playing the violin. And Mesi Paladi-Kovacs, as the no-nonsense charwoman, speaks for a humanity that cuts across class and status. It’s she, far more than the proud and proper Samsas, who accepts Gregor for what he’s become.

Some aspects of the script did wear on me – there’s a glut of meta-theatrical scene-setting before the story gets underway – but that does nothing to detract from a persuasive and disciplined cast. Their crisp, inventive stagecraft brings new vigour to an iconic work. And as they invite us to reconsider the whole concept of “normal”, the most meaningful metamorphosis might be our own.