Slightly less mysteriously titled ‘Mathematician in Wonderland’ in Korea, a national lust for mathematical excellence at school is combined with calculus as this beautiful, if not outright sexy, part of the national psyche.

It also combines another familiar Korean cinema theme in covering relations with North Korea, and stirs in some broader cinematic tropes such as the grumpy adult-helpless youth friendship and the secret genius blue-collar worker.

A breakout role for Kim Dong-hwi, who probably had the somewhat surreal experience of cutting his cinematic teeth opposite Korea’s most established long-term star, Choi Min-sik (Oldboy, I Saw the Devil).

Kim plays Ji-woo, a welfare recipient student who has gained a place at a prestigious for the gifted, complete with knitted white jumpers fit for an obscure English sport. His lowlier background holds back Ji-woo, but so does his maths ability in this gaggle of young geniuses.

Faced with a transfer to a standard state-backed school, he stumbles upon the vast mathematical abilities of the school’s security guard, Hak-sung (Choi). Ever the surly character inclusion, Choi plays a typically frown-faced addition here, but one partly tortured by his unused genius.

Choi is also reprising his role as a North Korean, previously seen in Shiri (1999), where he played a military spy from above the border. Here he is a defector who wanted a life in the South where we would be free to practice maths without its usage being weapon-based.

Hak-sung eventually agrees to tutor Ji-woo in secret, insisting the relationship stays focused purely on the act of maths problem-solving. Despite their outward differences, the two outcasts begin to find something in each other they were both sorely missing.

The above description – maths fetishisation – may seem a glib way to describe this film and perhaps something will be lost in translate for some international audiences. But for Koreans, especially those at such private school, the craft and success of mathematics can easily be seen as the foundation heartbeat of such a film.

This is a work with a heart of its own though, even as it begins to become embroiled in its own fanciful musings. Especially as maths is portrayed as the major battleground between North and South. This wider heart comes, as you may well expect, from that central relationship between Ji-woo and Hak-sung.

It might prove a disjoined watch for fans of Choi Min-sik most familiar with the blood-splattered ‘Oldboy’ and ‘I Saw the Devil’, but Choi still manages to carry that sense for foreboding and menace even as he is explaining maths problems.

Promoted as the Korean take on the US classic ‘Good Will Hunting’, it manages to inject enough distinctly Korean themes to avoid such a comparison becoming distracting. Despite themes of loss, North-South relations and, well, numbers, In Our Prime manages to stay largely light-hearted and upbeat. A comfort film for all, but especially those of a numerical persuasion.