Frank Sidebottom was an unusual figure in both character and form. He was not quite a musician, not quite a comedian, and wore a giant papier-mâché head with giant bug-eyes and a perpetual expression of shock. In the 80s and 90s, he achieved minor celebrity by touring his bizarre plinky-plonk keyboard music around the UK, as well as his continual appearances on regional television, but was simply just too weird to ever break into the mainstream.

This is not his story. Jon Ronson, the co-writer of Frank and one-time band mate of Frank Sidebottom, has taken Frank’s physical structure and eccentric spirit, but has injected it with the savant naiveté of Syd Barrett and the erratic genius of Daniel Johnston to create a character who is a tribute to the weird and wonderful fringe of popular music. Elements of the film are reminiscent of Jon Ronson’s account of his experience as a keyboard player for Frank Sidebottom’s Oh Blimey Big Band, including his serendipitous acceptance into the band because he knows how to play ‘C, F and G’. Domnhall Gleeson plays Jon Burroughs, the Ronson stand-in, whose quiet, awkward charm works well playing the outsider amongst a group of outsiders.

In Frank, Jon winds up playing keyboards for the curious American band Soronprfbs, a name none of the members knows how to pronounce. They are fronted by the enigmatic Frank, a man worshipped by the other members of the band who, unlike his real-life counterpart, never takes off his giant papier-mâché head. Jon relinquishes his boring suburban life living with his parents to join Soronprfbs somewhere in Ireland. They embark on an exhausting year-long toil at making an album that recalls the eerie stories of the recording of Trout Mask Replica by Captain Beefheart.  Jon falls under the spell of Frank, and Frank takes a shine to him too despite his banality and lack of talent, to the bemusement of his fellow bandmates.

The film starts out quirky and eccentric, as one might expect, with fun scenes of the screwy ways in which they try to record the album, but as Jon’s admiration for Frank and desire to be creative and accepted by his disdainful bandmates grow, it gradually shifts to a darker, more disturbing tone. The film tackles ideas about creativity and madness, and challenges conventional ideas about the link between the two, perpetuated by the tortured genius trope commonly found in our culture. Jon is convinced that Frank’s torment is the source of his genius, and seeks out torment of his own, but might Frank just be a talented man with a mental illness? The film also mocks the importance of having a large fan base through the tensions in the band over being ‘likeable’, as well as Jon’s incessant tweets we see throughout the movie, and his obsession with the hit counts on his Twitter and YouTube accounts. The film works largely because of the success of Michael Fassbender’s performance as Frank, whose restrictive mask forces him to act with the rest of his body, and gives life to Frank’s twitchy sage.

What is refreshing is how tactfully the character of Frank is handled. Frank is peculiar and unstable, but is never depicted as a freak. Instead, he is portrayed with affection and respect without glorifying his mental illness. This is a funny, moving and authentic examination and tribute to outsider musicians. This film may simply be too weird to be palatable for a mass audience, but as a tribute to eccentrics like Frank, Syd, Daniel and The Captain, it shouldn’t be any other way.