Billboard sat down with co-directors MacMahon and McGourty to learn how they locked in interviews with Page, Robert Plant and John Paul Jones, why the film stops after Led Zeppelin II and how some of the band’s contemporaries reacted to screenings of the movie.

Full of never-before-seen footage of the band’s first 18 months, interviews with John Paul Jones, Jimmy Page, Robert Plant, and new audio from the late John Bonham, the first authorised documentary about the best hard rock band to ever do it assumes a lot about what its audience already knows.

The release of the Becoming Led Zeppelin documentary pushes several albums by the band, including Led Zeppelin, Led Zeppelin II, and Four Symbols, up the UK charts.

Becoming Led Zeppelin', the first documentary in which the surviving members of the band have ever participated, is in theaters now

Led Zeppelin's surviving members come together for the first time ever to tell their amazing origin story and 'Los Angeles' talks to the pair who made it happen

DECIDER spoke to director-writer Bernard MacMahon and producer-writer Allison McGourty about this project that was decades in the making.