The rag-tag ‘chosen family’ thrown together through circumstance – sometimes a healthy splash of desperation, too – is a formula often used in storytelling, but rarely perfected. South Korean film Broker is one such rarity, with an abandoned baby forming the glue that knits disparate and, initially, opposing souls to one another.

The idea for the film came to acclaimed Japanese director Hirokazu Kore-eda (Shoplifters) when he learned of Japan’s only baby box – a system dating back to the Middle Ages, wherein unwanted newborns can be left in warm and secure boxes in the front of buildings, accessible from the outside, to be looked after by someone else. Broker begins with young mother Moon So-young (Lee Ji-eun, aka popstar IU) leaving Woo-sung, her child, at a church baby box. Woo-sung is then stolen by two ‘brokers’ – Ha Sang-Hyeon (Song Kang-ho, Parasite) and Dong-soo (Gang Don-won) – to be sold on the adoption black market. Police detectives Soo-jin (Bae Doona, The Host) and Lee (Lee Joo-young, Itaewon Class) watch on, hoping to catch the two criminals mid-sale.

A sudden change of heart brings So-young back into the picture and along for the ride with the brokers to look for suitable buyers for her son. Inevitably, the trio bond with one another, having a shared interest in rehoming the baby, and alignments and goals begin to converge and shift in interesting and unexpected ways as this unconventional road trip with an unconventional family unit rattles its way around the country.

The beauty of Broker is its ability to spin something dark into something surprisingly sweet and affectionate, without lessening its impact. The reality of poverty is illustrated in the brokers’ cobbled-together vehicle, while the reality of police work is days sitting in a car on a stakeout with no change of clothes and mounting empty food packages. Debates over whether baby boxes create ‘bad’ mothers – and how it feels to be one of those babies, or mothers – are confronted head-on, and while Hirokazu can’t provide any answers, he takes an implicitly non-judgemental stance. There are no heroes and villains here, just broken people trying to survive in a broken system that allows human beings to become castoffs. In the end, making the right decision isn’t about moral self-atonement but about the kind of selflessness needed to raise a child.

While every performance is deserving of praise, Lee Ji-eun’s is a standout, prickly yet deeply empathic, and effective with a simple sideways glance or a brief pause in dialogue. Hirokazu’s direction elevates these nuances wonderfully with subtle moments of tranquillity: a stray blossom on a watery car window; a hand covering a loved one’s face; two old friends kicking a can on a beach at sunset. There are echoes of Satoshi Kon’s Tokyo Godfathers in the ‘lowlifes looking after an infant’ plot, but Broker is something truly special on its own: a feelgood story that won’t leave you with a toothache, but certainly a tear or two.

Dir: Hirokazu Kore-eda (12A, 129 mins)

Broker is out in cinemas Fri 24 Feb

words HANNAH COLLINS