Tasked with following up the international success of the Vengeance Trilogy, Park provides a dippy rom-com of peculiar proportions, with no better setting for his manic story-telling than the blue-tiled walls of a mental institution.

Sometimes when a filmmaker has enjoyed such success for a certain strand of film, it makes sense to try something entirely different as a follow-up. Here Park departs from the blood-splattered violence of his famous trilogy and searches for eccentric laughs from a cast of mental hospital patients with differing quirks.

The film is as characteristically stylish as ever though, combining auteur-level framing with surrealist visualisation to create something habitually Park-like in the process.

Young-goon (Im Soo-jung) works in a factory making radios, but believes she is a cyborg and after attempting to “recharge” herself with a power cord at work, is institutionalised. Alongside this need to charge, she refuses to eat, opting instead to lick batteries.

After being admitted, she soon meets Il-soon (Rain), a young man with schizophrenic kleptomania who become fascinated with Young-goon.

It seems at first that violence, the mainstay of the Vengeance Trilogy, is likely to punctuate the film’s story, with Young-goon’s delusional voices telling her to kill the “white ‘uns”, or medical staff. With memories of her grandmother also being committed for her own belief in being a mouse, Young-goon feels she need to remove her capacity for sympathy so she can exact revenge.

What builds instead is a bond between Young-goon and Il-soon where each manage to find the missing pieces in the other’s company. Central to their battle for mental health is getting Young-goon to eat real food, a race against the clock where the logic of doctors fails and Il-soon's understanding becomes vital.

The apparent delusions of the patients are so superbly crafted on screen it is difficult to imagine them as anything but true to life, offering a sympathetic look into a world where such visions do appear entirely real to those imagining them.

The wider cast provides plenty of comic relief, from the patient who believes everything is their fault and chases anyone around to offer random apologies, to the portly acquaintance who will happily gouge on Young-goon’s food while she performs her battery licking.

What brings the film together so well is the intrinsic likability of the entire cast of patients. We feel the pain of their distresses, finding ourselves willing them along to their targets regardless of how obscure.

The hospital staff, which are so plentiful they seem to almost outnumber the patients, are portrayed as smiling assassins, happily providing electric shock treatment and overseeing hectic group sessions with jovial routine.

Many Vengeance Trilogy fans are likely to lead themselves to I’m a Cyborg and may feel displaced by the slower pace and comedic themes which seem a stark departure.

There is no doubt this is a change of pace and direction, but it is one that still works for Park, who has often invoked a peculiar sense of what is funny to build our empathy to the characters before us. By the film’s conclusion it is impossible not to be barracking for the patients’ joy, including the coming together of the unique love story which anchors its dramatic direction.