Opening the London Film Festival 2014 was the Oscar contender The Imitation Game; which, at it’s core, is a story of the underdog, of an outsider discovering himself as he uses his exceptional aptitude for mathematics to good use. Funnily enough, in a somewhat broad sense, this is also the outline to Morgan Matthews’ X+Y, the director’s first foray outside of documentary filmmaking – and what The Imitation Game succeeds on an emotional, captivating level, this earnest, moving picture more than matches it. The implications to this tale are not nearly as emphatic, but we’re equally as invested in the tale at hand.

Diagnosed with autism at a young age, Nathan (Asa Butterfield) has always been different from other kids. The one person who fully understood him, it seemed, was his father Michael (Martin McCann) – though he was tragically killed in a car accident, leaving his widowed wife Julie (Sally Hawkins) to care for their son. While the pair have struggled to form a congruous relationship, Julie signs Nathan up for special maths classes with former protégé turned unorthodox tutor, Mr. Humphreys (Rafe Spall). Nathan responds well, and years down the line qualifies for a prestigious maths tournament, as he sets off to Taiwan on a life altering vacation.

Each and every character that make up this engrossing tale – including the likes of tournament organiser Richard (Eddie Marsan) and fellow competitor Luke Shelton (Jake Davies) – are all so intricately layered and nuanced, each with their own palpable personality traits and character arc. They all serve a purpose, and many could have a movie of their own and it would equally as intriguing as Nathan’s. The only aspect to this narrative that isn’t quite so absorbing is the romantic sub-story between our protagonist and Zhang Mei (Jo Yang). While integral to the plot in regards to Nathan’s coming-of-age, it detracts heavily from the more subtle mother/son and teacher/student dynamics, which are far more compelling and emotionally engaging. It’s just a shame they are compromised and carelessly deviated away from in turn for a more conventional, and at times, mawkish romance.

Part of the reason why we crave more focus on the relationship between Julie and Nathan, is because Hawkins is nothing short of exceptional in the role. Her unconditional love for her son is so tangible and indisputable, while there’s such a sadness behind her eyes, and a fragility to her demeanour that serves the character so well. A special mention should also go to Davies, who is behind the most moving sequence in the film, playing the severely autistic Luke – not an easy role to get so right, but he excels tremendously.

X+Y is an emotional, upsetting piece of cinema that can be accused of veering into overtly sentimental territory on occasion (with a rather unsubtle use of music to indicate when we’re in for a disquieting scene). Yet it doesn’t take anything away from this intimate study of an outsider that is bound to move, compel and touch even the most hardened of punters. Though as interesting as this may be, I still have absolutely no idea what trigonometry means.