On 13 January 1968, Johnny Cash recorded his legendary live album at Folsom State Prison in California. 40 years later, the album hasn't lost a bit of its power. His children, former colleagues, and even some ex-prisoners and guards look back. Archive footage of life in the prison back then is interspersed with footage of how it is now, as well as still photography of the performance. The highpoints of the album make up the film's soundtrack, including songs like "I Got Stripes," "25 Minutes to Go" and "Cocaine Blues," while animations support the texts. Cash's reflections on playing for people who made the wrong choices in their lives can occasionally be heard in voice-over. The son of a poor cotton farmer in Arkansas, Cash often ended up in trouble because of his excessive drug use, so he'd been through the metaphorical mill and felt a clear connection to the men behind bars. And the feeling was mutual. By performing for society's outcasts, for those whom the state had reduced to a number, he wanted to make a contribution to reforming the American prison system and bringing the lives of the condemned out into the open.