A BRILLIANT YOUNG MIND Unlike you, this small child understands basic math.

DIFFERENCE IS SOMETHING to be celebrated, parents earnestly tell kids who don't fit in, trying to armor their children against the worst the world has to offer. When Nathan (Asa Butterfield) is diagnosed with autism, he's young enough to believe it when his dad tells him he has a superpower—that his faculty with numbers and patterns makes him special.

Which it does, of course, and he is—but by the time Nathan reaches adolescence, long after the death of his beloved father, he's also isolated, unhappy, borderline abusive to his mother (the wonderful Sally Hawkins), and singlemindedly fixated on earning a spot on the British team to compete in the International Mathematical Olympiad. When he wins a chance to train for the team, he leaves home and for the first time begins to grapple with his social limitations.

It's rare enough to see a movie about a kid with mental health issues who isn't a school shooter, but A Brilliant Young Mind is insightful and non-condescending as it portrays the coming-of-age challenges of a boy whose emotional wiring makes dealing with humans extra challenging. The film is at its best when documenting the dynamics between the genius-misfits on the math team—it's based on the 2007 documentary Beautiful Young Minds, about kids training for the British mathematics team, which is probably why its depiction of tiny math nerdlings rings so startlingly true.

Director Morgan Matthews elegantly dramatizes what might be going on in Nathan's head: At times, the camera becomes absorbed by colors and patterns, edging out all other visual information. Fronted by a strong performance from Butterfield, the film confidently walks a delicate line, showing how mathematics is at once the source of Nathan's isolation, and his way out of it.