Imagine a band where the singer is so painfully shy and awkward that he must wear a giant papier-mache puppet head ¡ª not only on stage, but pretty much all the time. That¡¯s the premise of ¡°Frank,¡± starring Michael Fassbender under the mask; a story loosely based on the beyond-cult indie musician Frank Sidebottom (aka the late Chris Sievey.)

It¡¯s another chapter in the myth of mental illness as pure rock ¡®n¡¯ roll ¡ª see Daniel Johnston, Iggy Pop, Syd Barret, Captain Beefheart, et al. The film starkly contrasts Frank¡¯s idiot-savant freedom with that of his careerist keyboardist Jon, (Domhnall Gleeson), who wants to rein in the band to be ¡°more likable¡± and play the industry game at Austin¡¯s legendary South by Southwest festival. Frank eventually collapses into a fit, shrieking at Jon ¡°You make music sh-t!¡±

¡°Frank,¡± which opens this weekend, is a wildly offbeat and amusing film, but while it differs in its puppet-head particulars, it treads an incredibly common path for this sort of musician-as-head-case story.