Forty years after Britain's foremost underground band released their debut album Piper at the Gates of Dawn, Pink Floyd remain one of the biggest brand names and best-loved bands in the world. This film features extended archive footage, some of it rarely or never seen, alongside original interviews with the four surviving members of Pink Floyd - David Gilmour, Roger Waters, Richard Wright and Nick Mason - and traces the journey of a band that has only ever had five members, three of whom have lead the band at different stages of its evolution.