This is the story of amateur dramatics in Britain. In a triumphant mix of memoir, social history, interviews and manifesto, Jenny Landreth opens our eyes to am-dram and shows us a vibrant world that is a crucial part of our culture.

Starting with the Mystery Plays of the Middle Ages, we move, via Shakespeare, to the Georgian aristocrats who built opulent private theatres in their own homes, then to the halcyon days of radical lefties taking political theatre to the streets and on to the present day. Along the way, we visit several thriving theatres - across the country, and beyond our shores - and meet a cast of characters who tell us about the joy amateur theatre brings them. And we follow the full arc of a production at the Midlands theatre where Jenny's parents met and she started out, from first auditions to last night party, with all the mishaps and forgotten lines that come in between.

In Britain today there are millions of people involved, and amateur theatre takes many forms, from classic productions to panto, but also cutting-edge new work. Without it, there would be no professional theatre, no Judi Dench or Kenneth Branagh or Brenda Blethyn. Break a Leg is an emphatic celebration. It is also a rallying cry, a call to appreciate how amateur theatre enriches communities and many people’s lives - and how, if you join in, it might just do the same for you.