A few years ago a survey found that a substantial number of parents believed traditional fairytales were too scary to read to their children. But maybe you can’t have the light without the dark, or the good without the bad? Maybe we need our villains in order to have heroes – and perhaps nobody is wholly a rotter or a saint? That’s the premise of this ingenious and often witty musical by Nancy Harris and Marc Teitler.

It begins with the Big Bad Wolf (Dean Nolan) about to gobble up Red Riding Hood when the story gets stopped by the police, apparently acting on the instructions of the Council of Bedtime Stories. While Wolfie protests that he’s only doing his job and the story can’t be finished without him, he soon finds himself sharing a cell with other storybook villains including Captain Hook (Miles Yekinni) , the Ugly Sisters (Claire Sundin and Kelly Agbowu) and Rumpelstiltskin (David McKay).

They are all accused of being way too bad for children’s good. Apparently modern kids only want the sunshine and smiles of the best-selling Fluffalo.

There is an element here of reclaiming characters in the tradition of feminist retellings, but Baddies also makes wider points about a culture where books come with trigger warnings and everyone fears causing either offence or trauma. It does this in a thoroughly entertaining fashion with the arrival of smug lifestyle guru Peter Pan (Christian Roe), and a butter-wouldn’t-melt-in-her-mouth Cinderella (Kathy Rose O’Brien) whose major concerns are air freshener and accessories. But maybe this Cinders isn’t good as gold after all.

Baddies is heavier on philosophy than it is on narrative, but develops into an unexpected riot. While the show needs tightening and could lose at least 15 minutes, it’s genuinely entertaining and original and should live very happily ever after at the Unicorn this winter.

• At the Unicorn theatre, London, until 24 December. Box office: 020-7645 0560