Michael Fassbender stars as frontman Frank, who hides his identity inside a massive cartoon head, just like Sidebottom’s, while Domhnall Gleeson plays keyboard player and aspiring songsmith Jon. The Irish actor was required to don the fibreglass headgear, normally worn by Fassbender, in one scene in the black comedy, which is loosely based on writer Jon Ronson’s experience performing with the mask-wearing creation of comedian Chris Sievey.
