South Korean film “Sleep” seems to be a certain kind of story and then ends up becoming something much different. This is an odd mix of horror thriller and black comedy swinging back and forth somewhere between “The Exorcist” (1973) and “Repulsion” (1965), and I appreciated this interesting genre hybrid even though I often observed its story and characters from the distance while being more aware of its plot mechanism.

The movie begins with the disturbing opening scene showing how something weird begins to happen for Soo-jin (Jung Yu-mi) and her husband Hyeon-soo (Lee Sun-kyun) in the middle of one night. She happens to see husband going through a sort of sleepwalking, and then she is more disturbed as things go bump in their little apartment no apparent reason. While she looks around here and there in the apartment, the movie naturally dials up the level of suspension and dread, and we accordingly get a nice variation of a certain genre cliché around the end of the scene.

However, Hyeon-soo does not remember anything about what happened to him at last night, and Soo-jin becomes more baffled and concerned as Hyeon-soo continues to show a series of peculiar sleepwalking behaviors. At one point, he suddenly seems to be so hungry that he devours a number of raw stuffs in the refrigerator, but, again, he has no memory about that at all, and that certainly unnerves Soo-jin more to say the least.

After Hyeon-soo almost gets himself killed later due to his ongoing sleep problem, he and his wife eventually go to a clinic for finding what is really happening to Hyeon-soo. The doctor is willing to help them as much as possible in addition to giving some advice in addition to prescribing a drug for Hyeon-soo, but that does not satisfy Soo-jin much. As things do not get better for her and her husband at all, she worries more while also coming to sleep less than before, and she has a good reason for that. She is currently going through the later stage of her pregnancy, and endangering her baby is surely the last thing she wants.

However, no matter how much she tries in one way or another, it seems that there is not any sensible way to solve their little domestic problem. When her mother drops by the apartment along with a shaman later in the story, the shaman ominously warns to Soo-jin and her husband that there is a ghost in the apartment, and that seems more possible to Soo-jin as she struggles more with her increasingly frustrating situation day by day. Is it possible that there is actually a ghost somewhere in the apartment? Is it really true that the ghost has some insidious purpose behind its frequent haunting of Soo-jin’s apartment?

As Soo-jin’s state of mind gets more troubled by this frightening possibility, the movie doles out more disturbing moments coupled with some dark sense of humor. Some of them may make you wince for good reasons, but the movie thankfully presents these scenes with enough skill and restraint at least, and you may actually be amused a bit by one particular scene which may take you back to that infamous moment in “Fatal Attraction” (1987).

Maybe she should have distanced herself from her husband from the very beginning, but Soo-jin lets herself stuck with her husband just because of her firm belief in marriage, and she becomes more obsessed with solving their domestic problem. Not so surprisingly, there eventually comes the breaking point for her, and that is where the movie becomes more ambiguous about what is actually going on around her.

Around that narrative point, director/writer Jason Yu’s screenplay puts more distance between us and its heroine, but the movie still holds our attention nonetheless thanks to Yu’s competent direction. As cinematographer Kim Tae-soo frequently stays around its two main characters in their supposedly cozy domestic environment, a sense of isolation around them feels more palpable along the story, and that is further accentuated by Soo-jin’s several absurdly drastic measures against her husband’s sleep problem. When their apartment is turned into something quite different around the end of the story, we are quite surprised at first, but we also see the inevitability of this sudden change, and we come to brace ourselves as its main characters are driven further into their extreme circumstance.

The movie depends a lot on its two lead performers, who show considerable commitment as their respective characters swirl around each other from one end to the other. While Jung Yu-mi does a good job of embodying her character’s gradual emotional disturbance along the story, Lee Sun-kyun steadily functions as her solid counterpart throughout the film, and Kim Gook-hee provides a bit of cheerfulness at the fringe of the story as one of the neighbors in the apartment building.

On the whole, “Sleep” is a well-made genre flick to be admired for its commendable technical aspects, and Yu, who previously worked as the assistant director Bong Joon-ho’s “Okja” (2017), demonstrates his considerable filmmaking skills here. Although this is his first feature film, he clearly knows how to engage and entertain us, and it will be interesting to watch whatever will come next from him in the future.