You'd be forgiven for thinking – particularly if you'd watched the trailers, as I had – that Frank would be some ridiculous and zany madcap comical farce. And in fact – and despite being an ardent fan of Michael Fassbender and Domhnall Gleeson – I pigeonholed the movie for far too long on that basis; very foolish of me. It was only after I had come across Mark Kermode's review of the film that I decided maybe it was time to see why he had rated it so highly. Believe me, Frank is one of the most surprising films you'll ever see. So, what is it about? Directed by Lenny Abrahamson, Frank tells the story of Jon Burroughs (Domhnall Gleeson) who – after playing keyboard for the SORONPRFBS (don't worry, it's unpronounceable.) following the original keyboardist attempt to drown himself in the ocean – is whisked away by the band to Ireland for what he presumes, is a weekend gig. What should have been a short weekend away quickly turns into a considerably longer affair due to the band's unusual way of recording material. Jon struggles to find his place within the band; finding ardent indifference in Baraque (François Civil) and Nana (Carla Azar) and encountering outright hostility from Clara (Maggie Gyllenhaal) who threatens to stab him for various reasons on more than one occasion. The band's manager, Don (Scoot McNairy) and enigmatic but charismatic lead singer, Frank (Michael Fassbender) on the other hand, are much more accommodating; Jon quickly starts to become more and more obsessed with Frank. Frank is based on the writings of Jon Ronson and inspired by his time playing in Chris Sievey's alter ego, Frank Sidebottom's group, the Oh Blimey Big Band. It's worth noting this is not a biopic; more an amalgamation of influences ranging from the obvious, Frank Sidebottom, to characters such as Captain Beefheart and Daniel Johnston. Frank can best be described as a dark comedy: yes, it's funny, but not in the way you might expect. The humour lies within the cast's nuanced performances; in the absurdity of their characters personalities and situations, they find themselves in: its intelligence and understated nature are its strength and are the result of an excellent script, and an inventive and magnificent cast. Perhaps more surprising is the melancholia surrounding the movie and its characters. Frank can be an incredibly funny movie, but it's also replete with sorrow and dejection and regret: it explores and challenges the established conventions which suggest that genius and madness are somehow intertwined; tip-toeing the line adroitly and unravelling an enigma that's both heartbreaking and poignant. It's a film which is, at its centre, about mental illness; exploring this sensitive subject with a delicacy and intricacy rarely seen. Not something I expected from a film I'd assumed would be more akin to a slapstick comedy. Frank is the enigma of whom I speak, and to say he's complicated is an understatement. Fortunately, he's portrayed by one of the greatest, most idiosyncratic talents of our time, Michael Fassbender. The nuances Fassbender brings to the role are numerous (far too numerous to go into detail) and ranging; from the over the top eccentricities to the subtle mannerisms which cleverly hint toward the unveil at the end of the movie: impressive considering any sentiment or response had to come entirely from body language due to Fassbender having to wear the Frank mask throughout 95% of the movie. Frank is such an attention-grabbing, larger than life character, dominating the screen from beginning to end, it's easy to forget this is Jon's story, not Frank's. It's fortunate then we have the wonderful and endearing talent of Domhnall Gleeson to keep us grounded; preventing us from being completely swept away by Frank's almost whimsical nature. Gleeson has the most extraordinary ability to stand out on-screen; projecting his presence throughout a movie, whether in a lead or supporting role. More importantly perhaps is the fact that not only is he strong enough to play lead alongside the likes of Fassbender, but that he's quite willing and knows when to take a step back; allowing others to take the stage. Gleeson's character, Jon, has an awkward naivety about him; an outsider, almost underdog kind of vibe which masks the fact that he's actually rather ambitious and self-centred — which rubs Clara, in particular, up the wrong way. The cast of characters of whom forms the band is brilliant throughout, with Maggie Gyllenhaal (as Clara) delivering a particularly well-received performance. However, I would argue that one of the most outstanding performances of the film was also one of the most underappreciated — that of Scoot McNairy as Don. McNairy presents an ingenious and abstruse performance as Don, the band's manager; a man living constantly on the knife-edge of sanity, threatening to topple at any moment. In many ways, Don is a metaphor for the film as a whole; mysterious and endearing, but wracked with demons. He's arguably one of the most fundamental characters, being the individual who not only brings the group together but also holds them together; containing their eccentricities: something which inflicts a terrible toll on him. McNairy's role in the film is really downplayed, and he does a really good job of fading into the background; getting lost amongst the rest of the cast: as such, it's facile for the audience to relegate and forget about him. This isn't a criticism; it's a conscious decision made by the filmmakers, one which works really well; mirroring Don's character arc: both the filmmakers and McNairy deserve far more credit than they seem to have got. Frank is the kind of movie that gets better the more you view it: it leaves you contemplating the characters, their relationships, and their actions, long after the film has finished. The use and importance of music in Frank make this more akin to a musical in many ways, and the decision to have the music performed by the actors themselves bestows a tangible physicality to the film. As I feel I've waffled on for far too long already, I'm going to quickly wrap it up here. I'll end by simply saying, I love this movie: it will make you laugh, it will make you think, and it will make you cry, and, by the end, it will leave you feeling profoundly uplifted.