My friends are split into two categories – those who smile when I say Frank Sidebottom, and those who look at me a bit strangely. And even more strangely when I describe him, and maybe sing a line or two from Guess Who’s Been on Match of the Day… He was a legend, and when Chris Sievey (the man inside Frank’s head) died penniless in 2010, his fans put their hands in their pockets and paid for his funeral.

There are two Sidebottom films coming this year. Frank, the first one to be released, is a fictional tale of another Frank, played by Michael Fassbender, complete with the spirit of the original, but with an American accent and, I suspect, a rather more honed physique (the other is a straightforward documentary). If you’re expecting a biopic from Frank, you’ll be confused. Very confused. Actually you’ll be a bit confused whatever you were expecting. But in a good way.

Directed by Lenny Abrahamson and co-written by Jon Ronson (who played keyboards with Frank Sidebottom’s Oh Blimey Big Band) this is an affectionate homage to Frank the character, some of it loosely based on Ronson’s own experiences. It’s a quirky tale of an extremely avant-garde band with an unpronounceable name (Soronprfbs) whose charismatic lead singer is never seen without a large papier-mâché head. He even showers in it.

The story is told by Jon, a geeky type of limited musical talent who dreams of rock stardom. When he gets the chance to play keyboards for the Soronprfbs, things don’t quite turn out how he expects and he finds himself shut away in a cottage in Ireland with his bandmates, all of them quite mad (they met in a mental health institution). The band are pretty much held hostage and bullied into creating something that might just be quite spectacular by the man with the big head. Jon sees something special in Frank, and has ambitions far beyond the walls of the cottage. But when he misjudges the band’s underlying wishes and sets them on the path to fame and fortune that he alone craves, things start to go a bit titsup.

Fassbender is properly fantastic: there might only be one expression on that enormous head, but somehow he fills those big eyes with emotion – maybe it’s in the shoulders, I don’t know. He makes him a bit sexy too, frankly. I know that’s weird. Maggie Gyllenhall is excellent as his terrifying girlfriend Clara who plays the theremin as if it’s a PMT transmitter, and Domnhall Gleeson gives Jon just the right amount of thrilled terror and feckless ambition.

There’s something gloriously life-affirming about Frank, it’s hilarious and bonkers in equal parts but also full of genuinely touching moments – I can’t deny that there was a tear in my eye at the end.

Go see Frank, you’ll love it. You know you will, you really will.

Here’s a little treat to give you a taste of the joy of Frank