The head seems like the kind of amusing stunt David Byrne might have attempted back in the halcyon Talking Heads days, except for one thing: Frank never removes the beach-ball sized orb, even during what seem like normal conversations with his bandmates.
The look of the head is interesting for its near parodic ordinariness. The artificial head boasts a modest haircut, large blue eyes that look as if they might have been appropriated from one of those annoyingly wide-eyed Margaret Keane paintings and a perpetually open mouth.
Director Lenny Abrahamson and Fassbender use the disguise without undue flourish, a wise choice because it's weird enough without being italicized.
The band, by the way, is called Soronprfbs, an unpronounceable name that suggests that this group of musicians couldn't care less about how their music is received.
The story focuses on Jon, a keyboardist played by Domhnall Gleeson. Jon joins the band by accident after the group's keyboardist attempts suicide.
Jon soon finds himself spending almost a year with the group in a secluded hideout where Frank inches his way toward Soronprfbs' first album.
The rest of the group is far from hospitable. Maggie Gyllenhaal appears as Clara, a woman who plays theremin and who makes no attempt to conceal her contempt for Jon, whose often cheery voice-over narration creates an ironic counterpoint to reality.
The group also includes the band's manager (Scoot McNairy), a drummer (Carla Azar) and a French-speaking bass player (Francois Civil) who also loathes Jon and regards him as a smiling no-talent.
The movie breaks its isolation when Jon arranges for the band to perform at South by Southwest in Austin, Texas, a spawning ground for cutting edge bands.
Not surprisingly, Frank is ill-equipped for a coming-out party, and Gyllenhaal's Clara seems to view the entire idea of "entertaining" as a sell-out.
I've read that the movie is a riff on the real-life experiences of co-writer Jon Ronson, who wrote the screenplay with Peter Straughan. Ronson evidently worked with Chris Sievey, a British musician and comic who died in 2010. Sievey created a character named Frank Sidebottom, who wore a head very much like the one donned by Fassbender in the movie.
You don't have to know anything about that backstory to appreciate Abrahamson's movie, which deals with the fragility of genius in a way that can be quietly funny.
Jon attempts -- rather foolishly it seems -- to bring Frank's talents to a wider audience, something that takes its toll on Frank and leads to a finale that's mildly redemptive and touching in a bittersweet way.