Out in cinemas this week is Frank, an offbeat comedy about an avant-garde band led by a singer who insists on wearing a giant Papier-mâché head at all times. Starring Domhnall Gleeson, Maggie Gyllenhaal and Michael Fassbender as Frank, this is a fresh and funny movie about celebrity, integrity and madness.

Gleeson, who has just landed a major role in the new Star Wars film series, is great as Jon, an irritating yet lovable English loser in the mould of David Brent or Alan Partridge. Brought in to the group at the last minute, he's a complete fish out of water in Frank's band, as they hole themselves up in a remote shack in the middle of Ireland in order to work on their album. The other members treat him with disdain, except for Frank, who despite never revealing his face, starts to open up.

To call it a left-field role for Michael Fassbender is understatement. There's something wonderfully audacious about having a major Hollywood star in your movie, only to never show his face. But Fassbender gives a real aura to Frank, and with the extremely deep David Byrne-styled voice he puts on, provides the film with some its funniest exchanges.

Co-written by journalist Jon Ronson, the film is inspired by his time playing keyboards for Frank Sidebottom, a cult comedy and music performer from the north of England famous for wearing that giant fake head. Here Frank is a mentally ill American musician rather than a Mancunian comedian, but this spiritual biopic contains the same anarchic spirit of Sidebottom's performances.

Director Lenny Abrahmson also adds some neat innovations, such as having Jon's tweets appear on screen, and a hilarious use of singing voiceover, and his long-time collaborator Stephen Rennicks provides a brilliant avant-garde rock soundtrack.

Surprisingly few films are made about the creative process, but Frank succeeds in capturing the chaos and community that is formed from such people working together, as well as looking at the dichotomy of celebrity vs artistic integrity, and whether you need to be tortured in order to be a genius.

Most of Frank is fun and forgettable, but there are some moments, especially the band's final performance, that will linger long after the credits roll.

Frank will be released in cinemas nationwide from 9 May.