Call it whatever you want—jailhouse rock, incarcerated funk, prison soul. But any way you slice it, Edge of Daybreak’s Eyes of Love is a singular achievement in music history. Recorded live in prison by incarcerated musicians during a strict five-hour window, this 1979 record is an improbable soul music sensation—worlds apart from records such as Johnny Cash’s At Folsom Prison, which was not actually recorded by inmates.

“It was years before I even knew it was a prison record—I had no idea about its history,” says Jon Kirby, a music executive, in Alix Lambert’s short documentary about the band. “It was just an incredible soul record from Virginia. It being recorded in prison was secondary to its sheer magnitude as a rare, obscure, incredible recording.”

Edge of Daybreak’s members, James Carrington, Jamal Jaha Nubi, Cornelius Cade, Harry Coleman, and McEvoy Robinson, met in Powhatan Correctional Center in Virginia, where they were serving sentences ranging from six to 60 years for armed robbery or assault.

Lambert’s film features an interview with Carrington. Dazzling, of-the-era graphics help illustrate the band’s inception, record release, and legacy. “I had very little B-roll and only a couple of pictures of the band back in the day,” Lambert told The Atlantic. “I had to think about how to tell this story creatively.”