Where can a tin of tuna buy you clean clothes? Where is it easier to get 'spice' than paracetamol? Where does self-harm barely raise an eyebrow?

Welcome to Her Majesty's Prison Service. Like most people, documentary-maker Chris Atkins didn't spend much time thinking about prisons. But after becoming embroiled in a dodgy scheme to fund his latest film, he was sent down for five years. His new home would be HMP Wandsworth, one of the largest and most dysfunctional prisons in Europe.

With a cast of characters ranging from wily drug dealers to senior officials bent on endless reform, this powerful memoir uncovers the horrifying reality behind the locked gates. Filled with dark humour and shocking stories, A Bit of a Stretch reveals why our creaking prison system is sorely costing us all - and why you should care.