In the late 1970s Britain, Joe Elliot joins a small time rock band that becomes Def Leppard. Soon taking control of the band with his perfectionism, Elliot and his mates strive to reach the top despite their personal strife that drives the less determined members away for more driven ones. By 1982, Def Leppard becomes a rock sensation, only to find that success has its own problems. Whether it be drummer Rick Allen's dismembering accident or guitarist Steve Clark's equally self-destructive alcoholism, the band struggles to keep the loyalty, tenacity and creativity that would make the group one of the greatest in rock history.