Kyung-min, a young single bank teller, lives alone in a typical South Korean apartment.  One day, she notices something amiss: her door lock cover has been left open, as if someone has tried to get in. Things go from bad to worse as Kyung Min goes from being stalked to being terrorized.

After a lifetime of J-Horror, K-Horror, and HK-Horror movies I thought I knew where Door Lock was headed. I assumed a young lady alone in a quiet apartment would be the subject of some kind of supernatural haunting, maybe some pale long-haired previous tenant crawling out of the sink, or a young child making screeching sounds while pointing out where he died.

Nope, it’s worse. The monsters in Door Lock are all too human.

When Kyung-min (Kong Hyo-jin) notices the first problem with her door lock, she calls the police just to make sure that she’s safe. The police are less than helpful, and chide her a little for bothering them. This is a bare glimpse of a major theme of the movie: young women in Korea are extremely vulnerable and the (mostly male) authoritarian figures can’t/won’t do much to help until it’s too late.

At work one day, Kyung-min mildly flirts with one of her customers, who then goes ballistic when she refuses to go to coffee with him. She is taken aback—is there something behind his outburst? Is he the one breaking into her apartment? Suspicions are high when he sees her again on the street later and grabs her, but she is saved by a coworker who drives by and offers her a ride.

The deeper the mysteries go, the more the men in her life completely abandon her. Her boss, the police, none of them are very helpful or understanding. She needs to start relying on herself (and her best friend) to get to the bottom of things.

It’s at this point that the movie really shines. Director Kwon Lee has a keen eye for suspense. When he uses the back streets of the Korean town like a maze, sending the camera gliding along with our heroine in ever more confusing turns, he never gives a hint as to what is behind the next corner. It’s tense.

There are even more utterly creepy scenes that I won’t spoil, but two of them made me gasp out loud. Kong Hyo-jin sometimes plays Kyung-min as a bit of a shrinking violet, frozen in fear as you’re screaming at her to get the hell out of there. Kwon Lee is obviously trying to point out how Korean society expects women to act, but it’s a little heavy-handed. Still, it’s a small price to pay for such an exceptional, effective, and somewhat gruesome thriller.

Door Lock premieres at the Fantasia Film Fest on July 24, 2019.