Mousetrap (들쥐) dropped on Netflix on August 28, right as I was leaving for my South Africa trip, so the timing couldn’t have been better. It felt like a while since I’d seen Ryu Jun-yeol in something new, and the trailer had exactly the vibe I wanted: thriller, psychotic, twisted, but not so heavy that it ruins your week. I ended up watching it across a string of long plane rides, and it was the perfect flight companion.
Content note: Mousetrap involves identity theft, violence, suicide, and some disturbing psychological themes. It’s rated 19+ in Korea and TV-MA in the US.
What it’s about
Moon-jae (Ryu Jun-yeol) is a successful novelist who hasn’t left his apartment in about three years. One day his fingerprint stops unlocking his banking app, and his life comes apart fast. His home has been sold, someone else is living as him, and a loan shark named No-ja (Sul Kyung-gu) is chasing him for money. Then, in an alley, he comes face to face with a man who has his face.
The show is built on an old Korean folk tale: if a rat eats your clipped fingernails, it turns into you. Moon-jae reluctantly teams up with No-ja to find “the rat” and prove he’s the real Moon-jae, while Detective Park Sun-yong (Lee Kyu-hyung) works a case that keeps pointing back to him. It’s directed by Kim Hong-sun, written by Lee Jae-gon, and adapted from Ludovico’s webtoon of the same name. All 10 episodes, roughly 50 to 65 minutes each, are on Netflix now.
Ryu Jun-yeol, twice
Mousetrap is Ryu Jun-yeol’s first dual role, and honestly, he’s the reason to watch. He plays the frazzled, fragile Moon-jae and the calm, cold impostor, and the way he switches between them gave me chills. At one point I genuinely wondered if he was a little psycho himself, which I mean as a huge compliment. He said in interviews that he went back and forth between the two characters’ makeup three or four times a day, which makes it even more impressive that they feel like two completely different people.
The scenes that stuck with me
The scene that hooked me early is Moon-jae sitting in his apartment with Su-hyeon, his accountant and only friend, who handles his phone and money for him, right after he’s been locked out of his bank accounts. Su-hyeon tells him, “I’ll get you out of this soon” (금방 나가게 해줄게), and it sounds like the comfort Moon-jae needs. Later you realize that line meant something much darker, and it’s the one I kept replaying in my head.
Another one I keep thinking about is when Moon-jae shows up at his high school reunion looking for Su-hyeon, shouting and making a scene to prove who he is. Nobody believes him. One classmate says he had drinks with Moon-jae just last week, and that’s when you really feel how helpless he is.
Then there’s Sul Kyung-gu as No-ja. Their partnership starts as pure business, a loan shark protecting his money, but there’s a moment where No-ja puts himself on the line so Moon-jae can run. Whether or not Moon-jae has been telling the whole truth, the connection between them feels real by that point, and it gave the show more heart than I expected.
What worked, and what didn’t
The pacing is great. Ten episodes is just enough, and it never drags or rushes the reveals. The twisted story works, and by the end it actually delivers a lesson instead of just shocking you. I go into that in my ending post.
The one thing I didn’t love was the plastic surgery angle. Without spoiling how it’s used, it’s a classic device in thrillers like this, and it felt like an easy shortcut in a show that’s otherwise pretty clever. It didn’t ruin anything for me, but it’s the part I’d change.
Plenty of people clearly agreed it was worth watching. It hit #1 on Netflix’s daily Top 10 series chart in Korea three days after release and reached #8 globally on FlixPatrol around the same time.
Is it worth watching?
Yes, especially if you like psychological thrillers with a twist. I’d specifically recommend saving it for a free weekend and binging it straight through. I watched it in chunks between flights and kept wishing I could just keep going. It’s also a great pick if you love watching an actor really stretch, because Ryu Jun-yeol carries the whole thing.
As for how dark it gets, it’s rated 19+ in Korea and TV-MA on Netflix in the US, but honestly it felt less violent than I expected. I’d have guessed something closer to 15+. It’s tense and unsettling, but more psychological than gory. If you want something light and cozy, skip it for now. If you want something that makes you side-eye your friends a little, it’s perfect.