Mousetrap (TV series)

Summarize Fact Check

Jae Moon-je, a reclusive novelist, becomes desperate after a mysterious figure known as "The Rat" steals his identity and financial assets. To reclaim his life, he forms an unlikely alliance with No-ja, a loan shark-turned-private investigator, leading them into a tense manhunt to uncover the truth behind the identity theft and the dark conspiracy hidden beneath it. After a Cat Vs Mouse chase, Moon-jae confronts the Rat. Before Moon-jae was born his parents who had a history of mental instability adopted a child from a orphanage and named him Moon-jae. They were struggling to conceive and when they had conceived they returned the child to the orphanage and named their child Moon-jae, the mother wanting their biological child to be better than the first. Moon-jae inherited his mother's mental instability and psychosis, once burning down his own school because the police questioned why he signed up under a different identity, Moon-jae had done so as he wanted to be a better Moon-jae. Moon-jae kept quiet about how his mother killed both her and her father by crashing her car into the Han River. Whilst working as a police officer, Moon-jae, a chain smoker decided to join a writing club and fake being a student to be a better Moon-jae. There was a writing student named Yu-min. Yu-min and his partner Min-yeong were writing students and Yu-min was a talented aspiring writer who had laid out notes containing stories which he intended to publish. Moon-jae being psychotic spread rumors about Min-Yeong and Yu-min's sex life, which resulted in Min-Young dropping out of school, taking pills and eventually killing herself with said pills. Yu-min had intended to publish his novels to support his partner; however, by then Moon-jae had already published Yu-min's stories under his name, becoming a famous novelist after securing funds from the mafia boss Noja. Moon-jae being crazy and wanting to be a better Moon-jae was always jealous of Yu-min, desiring Yu-min's life and partner. Yu-min decided to get revenge for what Moon-jae had done to him by using mafia links to fake his death and escape his identity, and underwent plastic surgery to make himself Moon-jae's doppelganger. Moon-jae's consumption of pills for his insanity drove him further insane, making him believe Yu-min's writings and partner Min-yeong was his. Yu-min, now intends to make use of Moon-jae's reclusion to expose Moon-jae as the true Rat that stole his life. Moon-jae kills Yu-min and convinces the public that he has dealt with his imposter. Moon-jae cannot really write, however he realises that Yu-mins final novel will expose that he was the Rat the whole time. As the novel predicts, Moon-jae truly spirals into insanity, he is prevented from exiting his house as the remaining mafia member seeks the illicit money that remains in Moon-jaes possession.

Main

• Ryu Jun-yeol as Je Moon-jae, a novelist^[1]
• Sul Kyung-gu as No-ja, a loan shark^[1]
• Lee Kyu-hyung as Sun-yong, a detective^[1]

Supporting

• Park Yoon-ho as Seo Yu-min, Moon-Jae's college classmate
• Song Su-yi as Min-yeong, Yu-min's girlfriend
• Moo Jin-sung as Son Su-hyeon, Moon-jae's friend
• Lee El as Han Ji-hye, the editor-in-chief
• Jung Hee-tae as Kim Han-su, Chief of the Detective Division
• Lee Chan-yong as Min-ho, a detective
• Lee Kwan-hoon as Dong-cheol, a detective
• Shin Soo-ho as Han Chang-u, a detective
• Kim Sung-oh as Park Seung-gyu, the ringleader of multiple illegal activities^[1]
• Shin Chang-joo as Byeong-jun, Seung-gyu's subordinate
• Kang Bin as Byeong-ho, Seung-gyu's subordinate

Development and filming

Initially developed under the working title The Rat,^[2] it is a television adaptation of the Kakao Webtoon's Field Mouse by Ludovico, which was inspired by the traditional Korean folktale about a rat that assumes a human form by consuming human fingernails.^[3] Produced by Kakao Entertainment, C-JeS Studios, H House and Studio PIM, directed by Kim Hong-sun [ko], who helmed the first season of Voice (2017), The Guest (2018), Money Heist: Korea – Joint Economic Area (2022), and Dear Hongrang (2025), and written by Lee Jae-gon, who penned Special Affairs Team TEN.^[4][2]

Principal photography began in the first half of 2025.^[3]

Casting

In December 2024, Ilgan Sports reported that Ryu Jun-yeol and Sul Kyung-gu were in talks to star in the series.^[3] By May 2025, Ryu and Sul were confirmed to lead the cast.^[2] Moon Jong-il and Go Hyung-woo were cast in supporting roles in December 2025.^[5][6]

Mousetrap was first unveiled in January 2026, as part of Netflix Korea 2026 Slate and announced for a third quarter of 2026 release window.^[4] By the end of July 2026, Netflix confirmed that the series is scheduled to premiere on August 28.^[1]