The Netflix thriller Mousetrap (2026) centers its main mystery on a complex case of identity and asset theft. Across its 10 episodes, the story deepens the investigation by connecting the name Je Moon-jae to three different men.
Below, we explain each character connected to the identity at the center of the series’ mystery.
1. The isolated writer (Ryu Jun Yeol)
The central victim of the scheme is the reclusive writer known as Je Moon-jae. He rose to fame as a suspense novelist, but past trauma and a family history of depression aggravated his panic disorder, leaving him confined to his home for three years.
His isolation made him increasingly dependent on others, creating the perfect opportunity for an anonymous figure to steal his assets, his name, and the public reputation he had built.
2. The vengeful impostor (Park Yoon Ho)
The criminal figure known as “the Rat” is actually Seo Yu-min, the writer’s former college friend. The story reveals that Yu-min is the original author of the book that made the protagonist famous.
Driven by the destruction of his own future through intellectual theft, he changes his face and voice through surgery, blackmails the victim’s caregiver, and takes over the successful life he believes should have been his.
3. The detective and original identity holder (Lee Kyu Hyung)
The investigation’s final revelation confirms that Detective Park Soon-young was born Je Moon-jae. Separated from his family as a child and sent to an orphanage after a traumatic incident, he lost every connection to his original identity. The name was later given to his younger brother in official records—the reclusive writer known to the public as Je Moon-jae.
Yu-min’s plan adds another layer of cruelty to the mystery. He manipulates the police investigation so that the detective unknowingly pursues and helps destroy his own brother, without either man realizing that they are related by blood.
The ending of Mousetrap uses the loss of legal identity and generational trauma to show that the name Je Moon-jae ultimately belongs neither to the famous writer nor to the impostor, but to the detective who has been leading the case.