After the entertaining western romp that was Jee-woon Kim’s The Good, The Bad, The Weird, the South Korean director has returned to darker themes that are more reminiscent of his The Tale of two Sisters for his latest film.

When a young woman is stuck on the side of a road with a flat tyre, she patiently waits for the tow truck to arrive. While telling her boyfriend of her predicament, a man in a yellow van turns up and offers to help her out. As it turns out, help is the very last thing he has in mind, for he is a notorious serial killer and she, well, his next victim.

When her boyfriend Kim (Byung-hun Lee) is informed of what has happened to his girlfriend, he’s understandably devastated. Unfortunately for the killer Kyun-chul (Min-sik Choi), his latest victim’s boyfriend happens to be an Intelligence agent who can more than look after himself.

With grief clouding his judgement, Kim embarks on tracking down the killer, on his own time and in his own way. As an enforcer of the law, he doesn’t just cross the line he long jumps it. Even when he has the killer in his grasp, it’s still not enough; he’d rather have him suffer than just kill him. But by letting the killer go, Kim, still wrapped up in a world of hate and revenge, soon discovers that it wasn’t the best decision he’s ever made.

This may sound as if the film’s plot falls victim to a run-of-a-mill psycho killer hunt, but as Jee-woon has proven in the past, he’s not one for conventional storytelling.

The film has a highly strung psychological twist to it, which sees a once duty-bound officer of the law slowly turn into the type of monster he’s chasing. Kim becomes so transfixed by revenge that he loses all sense of right from wrong.

Jee-woon focuses on the relationship between his two leads, fascinated as he is by how similar they become by the end. He uses horrific moments to highlight these similarities, as opposed to using them to merely shock his audience. In doing so he creates a thriller with horrific scenes, instead of just an all out horror film.

What he also does is communicate more about his central characters with a greater intensity visually rather than with dialogue. The director is fascinated with colours throughout and uses them to good effect. His cinematic palette manages to heighten mood and emotion in key scenes with startling results.

But although it looks stunning, the script – and in particular, the moral ambiguity that surrounds its ‘hero’ – throws doubt over Kim’s actions. Would someone in that position really put the lives of others in the way merely so he could get his revenge? It’s a tough ask for your audience to swallow and it’s not one that can be accepted likely.

Sweeping the moral hoo-hah aside, I Saw the Devil is a slick and bloody thriller. Min-sik puts in a great performance of a seemingly ordinary man on the outside, who embraces evil with open arms. He manages to tap into a darkness and revel in it on screen. If this was a US film, his character would no doubt star in numerous sequels, as is the way sick serial killers are dealt with in the West.

This may not be Jee-woon quite at his best, but he once again proves that the devil truly is in the detail.