The Mousetrap Netflix cast is led by Ryu Jun-yeol as Moon-jae, Sul Kyung-gu as Noja and Lee Kyoo-hyung as detective Sun-yong. The 10-episode Korean limited series premiered on Netflix on August 28, 2026. It turns identity theft into a physical nightmare: a reclusive writer discovers that someone who looks exactly like him has taken his name, money, digital access and public life.

This guide takes a case-file approach. It separates confirmed cast information from theory, explains the Korean folktale and Field Mouse webtoon behind the drama, and provides a spoiler-light map of all 10 episodes. That distinction matters because the show invites viewers to mistrust almost everyone.

Mousetrap Netflix cast and characters at a glance

The compact lead trio is one of the series’ strengths. Moon-jae supplies the panic, Noja brings danger from outside the law, and Sun-yong provides the procedural thread. Their stories begin at different points, but Netflix’s official descriptions make clear that the same criminal design is tightening around all three.

Ryu Jun-yeol as Moon-jae: the man being erased

Moon-jae is not simply a victim who loses a password. He is a successful novelist who writes under a pen name and has barely left his home for years. That isolation makes him an unusually vulnerable target. Other people know his work, but relatively few know the private person behind it. When his fingerprint stops opening his phone and his accounts no longer recognize him, he cannot rely on an ordinary public identity to prove who he is.

Ryu Jun-yeol has to play two kinds of fear at once. The first is practical: money, access and legal standing are disappearing. The second is existential: a doppelganger is apparently better at performing Moon-jae in public than Moon-jae is. The role works because his reclusiveness is not background decoration. It is the opening that allows the impostor to move in.

Viewers coming to the series after character-heavy thrillers may also like our Bodies cast guide, which similarly tracks people whose identities and timelines become part of the mystery.

Sul Kyung-gu as Noja: the dangerous counterweight

Noja is described by Netflix as a fierce loan shark. In a more conventional thriller he might be the person Moon-jae fears most. Here, he becomes another route into the larger scheme. His world is built on leverage, intimidation and knowing exactly who owes what. Identity laundering attacks the very records and relationships that make that power possible.

Sul Kyung-gu gives the plot a harder edge. Moon-jae responds like a man whose life is being overwritten, while Noja responds like a man accustomed to making threats rather than receiving them. Putting both characters in the same trap lets the series ask a useful question: does power protect a person when the system no longer agrees that he is himself?

Lee Kyoo-hyung as Sun-yong: the connecting investigator

Sun-yong is the detective chasing The Rat and attempting to connect events that initially look unrelated. He is the viewer’s best route through the evidence, but the episode descriptions also indicate that his own past becomes relevant. That prevents him from functioning as a neutral exposition machine. He has something at stake when the investigation turns toward the origin of the deception.

The balance among the three leads is important for searchers looking for the Mousetrap Netflix cast. This is not a large ensemble mystery where dozens of names require memorization. It is a three-sided pursuit: the writer who has been replaced, the loan shark who discovers a market for stolen lives, and the detective trying to identify the mechanism behind both.

What is The Rat in Mousetrap?

The Rat is the name attached to the identity thief at the center of the series. The label connects the modern crime to an old Korean folktale in which a rat eats a person’s discarded fingernail clippings and transforms into that person. Netflix uses that unsettling story as the drama’s conceptual engine. A small, ignored piece of you becomes enough for something else to imitate the whole.

The series translates that fear into the digital age. Fingerprints, passwords, financial records, public appearances and trusted witnesses all become modern versions of the fingernail clipping. Each is only a fragment of identity, but together those fragments can persuade the world that the copy is authentic.

How the Field Mouse webtoon connects to the Netflix series

Mousetrap is based on the webtoon Field Mouse. The adaptation keeps the central doppelganger and stolen-identity premise, then shapes it into a 10-part screen thriller under director Kim Hong-sun. The webtoon connection is more than a credit for fans to notice. It explains why the story feels like a fable being tested against phones, databases and surveillance.

Netflix’s official announcement foregrounds both the webtoon and the folktale, which is a strong signal about how the show wants to be read. The mystery is not only who stole Moon-jae’s life. It is also which parts of a person can be copied, which parts require memory, and whether society recognizes identity through inner truth or through documents and behavior.

Mousetrap episode guide: the evidence trail

Netflix lists the chapters at roughly 49 to 63 minutes. Because the whole season launched at once, the series is designed for viewers to carry details forward: a password failure in an early episode may matter as much as a more dramatic confrontation later. The table above stays close to Netflix’s published episode descriptions and does not turn marketing summaries into invented plot facts.

Mousetrap ending guide: what can be confirmed

Spoiler warning: the final episode is framed as the point where the network of lies and stolen identities comes into the open. Netflix’s official synopsis also emphasizes Moon-jae being pushed to question which person is the predator and which is the prey. That wording suggests the finale is built around a reversal of control, not merely the police revealing a name.

A responsible ending guide should distinguish a verified scene from an inference. The confirmed part is that the finale brings the accumulated deceptions into the open and forces the Moon-jae versus Rat conflict back to the idea of hunter and hunted. A more specific claim about a death, arrest or final identity would require a verified scene-by-scene account. This page will not manufacture one from a promotional synopsis.

If you enjoy Netflix mysteries built around an unreliable version of reality, see our Fool Me Once review and Squid Game character guide.

Is Mousetrap worth watching?

The strongest reason to watch is the premise. Most identity-theft thrillers concern stolen information; Mousetrap makes the theft embodied. Its villain does not only access Moon-jae’s life but performs it. The focused cast also makes the conspiracy easier to follow than a sprawling crime drama.

The best viewing strategy is to treat every identity claim as evidence. Note who recognizes a person without seeing documents, who trusts a device over memory, and who profits when identities become transferable. That approach makes the folktale connection useful rather than decorative.

Five clues to track on a Mousetrap rewatch

A second viewing should begin with access rather than motive. List every person who could reach Moon-jae’s devices, home, editor or unpublished work. Then note which security failure happens first. A fingerprint rejection, changed password and public impersonation require different levels of preparation, so their order can reveal how long the replacement plan was active.

Next, separate witnesses who recognize Moon-jae emotionally from systems that recognize him administratively. The drama repeatedly tests whether memory can compete with a clean digital record. Also watch moments when The Rat chooses visibility. An impostor who only wanted money would avoid attention, so every public appearance suggests that performance, punishment or control matters too.

Finally, track the language of predator and prey. The phrase becomes more meaningful when attached to Noja, a man accustomed to frightening others, and Moon-jae, a man forced out of isolation. The finale’s reversal is easier to read when viewers notice who sets a trap, who believes he controls it and who anticipated that belief.

The editor is another useful control point. Unlike a database, an editor can compare voice, habits and creative history, but personal familiarity can also be manipulated. Scenes involving manuscripts or professional memory help test whether authorship is the one part of Moon-jae’s identity that cannot be copied from a device.