If you’ve finished Mousetrap (들쥐) and you’re still sitting with that last scene, same. I binged it on flights during my South Africa trip, and the ending is the part I kept thinking about after I landed. Here’s how everything comes together, plus what I think the show was really trying to say.
⚠️ Spoilers below. This post gives away the full ending. If you haven’t watched yet, start with my spoiler-free Mousetrap review.
A quick recap
Moon-jae (Ryu Jun-yeol), a successful novelist who hasn’t left home in three years, gets locked out of his own life. His fingerprint stops working, his apartment has been sold, and someone with his face is living as him. Remember Su-hyeon (Moo Jin-sung), his accountant and only friend, promising “I’ll get you out of this soon” (금방 나가게 해줄게)? It wasn’t comfort. Su-hyeon was the one who handed Moon-jae’s home over, so the line really meant “I’ll get you out of your own house,” with nowhere left to go. It turns out the rat was forcing his hand by holding his daughter hostage, which makes the betrayal both colder and sadder. With loan shark No-ja (Sul Kyung-gu) dragging him along and Detective Park Sun-yong (Lee Kyu-hyung) circling, Moon-jae chases the impostor the show calls “the rat.”
The rat has a familiar face
The big reveal is that the impostor is Seo Yu-min (Park Yoon-ho), Moon-jae’s old friend from college. Yu-min sold his own identity into a network run by Park Seung-gyu (Kim Sung-oh) that erases people and recycles their identities, faked his death, and had plastic surgery to look like Moon-jae. Then he took over Moon-jae’s life piece by piece.
I mentioned in my review that the surgery part felt like a shortcut, and I still think that. But who’s under the surgery is the interesting part, because it sets up everything that comes next.
The cruise ship
Moon-jae finally tracks Yu-min down on a cruise ship, determined to end it. They fight, and Moon-jae throws Yu-min overboard. For a moment it feels like the real Moon-jae has won and the rat is gone.
Then the show flips everything. Back in college, Yu-min was the more talented writer. Out of jealousy, Moon-jae spread rumors that drove Yu-min’s girlfriend So Min-yeong (Song Su-yi) to take her own life, and then he built his career on Yu-min’s unpublished work. So the man we’d been rooting for as the victim was the one who stole a life first. Yu-min wasn’t just taking Moon-jae’s identity, he was taking back what Moon-jae had stolen from him. That was the moment the whole series clicked for me.
What happens to No-ja
No-ja doesn’t die, though Seung-gyu’s crew does everything they can, at one point burying him alive before he claws his way out. He comes out of it with a right arm he can no longer use, and he chooses not to get it treated, accepting it as the price for his past. He turns down Moon-jae’s money, warns him to hide well from Seung-gyu, and goes back to his hometown to live a normal life. After the way he put himself on the line for Moon-jae, it’s quiet and a little sad, but of everyone in the show, he’s the one who actually chooses to stop being a rat. Sul Kyung-gu has said there’s no season 2 planned, so this is where his story closes.
The final scene
Moon-jae technically gets his life back. He tries to go back to writing and struggles badly, because the genius was never really his. He receives Yu-min’s unfinished sequel manuscript, which would expose him if it ever saw daylight. He ends up shutting himself in his apartment, not enjoying any of the fame or money he fought so hard to reclaim, basically living like a rat in its hole. In the final moments he sees Yu-min at his door, but the knock is Seung-gyu, very much real and still there to collect what he’s owed.
What I think it means
I found the ending quite impressive, because it doesn’t punish Moon-jae with prison. It punishes him with himself. He gets everything back and can’t enjoy any of it, because none of it was ever his. A borrowed success turns out to be its own trap, which makes the title Mousetrap land a lot harder by the last episode.
It also changed how I saw the first episodes. That desperate man at the high school reunion, shouting that he’s the real Moon-jae, was telling the truth about his name and lying about almost everything else. I think that’s the lesson the show wanted to leave us with, and it’s why the twist works even with the plastic surgery shortcut.