X+Y (2015)

X+Y arrives as a British drama of modest ambition and genuine tenderness, following Nathan Ellis, a mathematics prodigy on the autism spectrum, from a childhood marked by his father's death to the International Mathematical Olympiad. The film's central achievement is its portrait of neurodivergence, built patiently around Nathan's sensory aversions, his difficulty reading social cues, and the way numbers offer him a grammar for a world that otherwise refuses to parse. Asa Butterfield plays the interiority without ornament. This is the rare case where a condition serves as the engine of the story instead of a decoration applied to it, and the film earns its place in that narrow category.

The romance with Zhang Mei, played by Jo Yang, gives the picture its second axis: a cross-cultural courtship conducted largely in silence and misread signals. That the story involves a British boy and a Chinese girl matters to the plot, though the film declines to interrogate what race means in either country. Sally Hawkins invests the mother with real weight, which makes the screenplay's decision to convert the real-life female mentor into Rafe Spall's Martin a curious bit of housekeeping. The historical record, meanwhile, has been rearranged with enthusiasm: a dead father who is alive, a Slovenian Olympiad relocated to Cambridge, a training camp moved from China to Taiwan. Dramatic license, all of it, exercised without evident ideological purpose.

Where the film could have lectured, it mostly chooses to sit quietly. The messaging is implicit, the lessons about love and connection delivered through behavior instead of speeches. That restraint is the film's saving grace. A tender, well-mannered picture, competently made, and content to let its audience do the arithmetic.