AllMovie

A hopeful musician named Jon (Domhnall Gleeson) joins an eccentric pop band led by an eccentric creative mastermind named Frank (Michael Fassbender), who conceals his true identity beneath a giant paper mache head. Frank supposedly adheres rigorously to the ethos of making music purely for the joy of doing it, but as Jon's influence in the band grows, Frank proves to be capable of a less-enlightened view.