Mousetrap Ending Explained: Who Is the Rat, Full Cast, and Where to Stream (2026)

A man wakes up, and his own fingerprint no longer opens his phone. That’s the pitch Netflix used to sell Mousetrap before it premiered, and by the time the finale lands, the show has quietly swapped out who you’re supposed to be rooting for.

When I checked the recap coverage from two separate outlets that specialize in Korean drama ending explainers against each other, both landed on the same twist: the reclusive novelist played by Ryu Jun-yeol isn’t the wronged party he appears to be for most of the runtime. That kind of agreement between independent recaps is usually the first thing worth confirming before writing about a finale this twisty.

Before You Read Further, Here’s the Setup

• Who Is the Rat in Mousetrap?
• How Does the Ending Actually Play Out?
• Full Cast: Who Plays Who in Mousetrap?
• Why Did Critics Split on Mousetrap?
• Where Can You Stream Mousetrap Right Now?

Who Is the Rat in Mousetrap?

Je Moon-jae wakes up to find that someone has taken over his identity down to his fingerprint, and the show spends its first several episodes framing him as the target of a mysterious figure everyone calls the Rat.

The finale reverses that framing. Moon-jae’s real name is Park Chan-u, and years before the events of the series he assumed the identity of Je Moon-jae — taking the place of his own older brother within their family. The person hunting him in the present, a man named Yu Min, isn’t a random impostor. Yu Min is someone Moon-jae wronged years earlier, back when Moon-jae published Yu Min’s stolen literary work as his own.

Reading both ending-explained recaps side by side, the detail that stood out is how deliberately the show buries this: the “victim” narrative holds up for roughly nine of the ten episodes before the reveal recontextualizes everything that came before it.

How Does the Ending Actually Play Out?

The confrontation between Moon-jae and Yu Min happens aboard a ship heading to Jeju, away from the detective work and loan-shark muscle that drives most of the middle episodes.

Yu Min goes overboard during the struggle and drowns, and the show never recovers a body. That absence of physical evidence matters a lot for how the finale resolves: Detective Sun-yong, who by blood is actually Moon-jae’s real brother, works out what happened but can’t prove murder without something to point to.

Moon-jae walks away legally clean and gets his stolen name back through the courts. He doesn’t walk away whole. Both recaps describe him ending the series isolated and unable to write, which reads less like a happy ending and more like the show’s actual verdict on him — that the identity thief everyone feared was, underneath it, the real predator in the story.

No-ja, the loan shark who runs a private detective operation and gets pulled into the search for Yu Min, loses the use of his right arm in the struggle. It’s a small detail, but it’s the clearest physical cost anyone in the cast pays for getting close to Moon-jae’s secret.

Full Cast: Who Plays Who in Mousetrap?

Ryu Jun-yeol and Sul Kyung-gu share the screen for the first time here, and the rest of the cast fills out around that pairing.

This is the first time Ryu Jun-yeol and Sul Kyung-gu have worked together, which is part of why the casting news traveled fast when it was first announced — two actors from very different generations of Korean cinema sharing a two-hander mystery premise.

Why Did Critics Split on Mousetrap?

The reviews that came in right after the August 28 premiere agree on the performances and disagree on the pacing.

Ryu Jun-yeol and Sul Kyung-gu make even the slower stretches watchable, according to multiple reviews published in the days after release, and the central concept — identity theft escalating into something closer to a psychological trap — gets consistent credit for being genuinely unsettling rather than just a gimmick.

The complaint that shows up almost everywhere is length. Ten hour-long episodes is a lot of runtime for a mystery that some reviewers felt could have landed the same twist in seven or eight. One review scored it 3.5 out of 5 specifically because of that stretch in the middle episodes, even while praising the finale’s reveal.

When I checked several of the post-premiere reviews against each other, the same split showed up almost every time: strong marks for the two leads, tired complaints about the middle stretch. Honestly, that split is fairly normal for identity-swap thrillers on this scale — the format tends to front-load intrigue and can sag once the audience has already guessed the general shape of the trick, even if the specific reveal still lands.

Where Can You Stream Mousetrap Right Now?

Mousetrap is a Netflix original, and all 10 episodes are already available worldwide with no regional delay — there’s no separate Korean broadcast window to wait out, unlike some tvN co-productions that stagger their Netflix release.

A standard Netflix subscription in your region covers it; no separate rental or premium add-on is required since it’s produced as a Netflix original rather than a licensed acquisition. If you’re outside Korea and searching for the title, use the English name “Mousetrap” rather than the Korean title 들쥐 or its literal translation “Field Mouse” — Netflix’s own search and the Tudum rankings both index it under the English title.

You’ll probably notice it sitting in Netflix’s non-English Top 10 chart in the days right after release, alongside whatever other K-drama or international title is trending that week. That list resets often, so a specific rank on a specific day isn’t worth chasing — the show either holds attention through word of mouth past the first week, or it doesn’t.

Before You Binge This One

• ✅ Go in expecting a slow build. The mystery rewards patience more than it rewards binge-speed viewing.
• ✅ Pay attention to Detective Sun-yong early on — his connection to Moon-jae isn’t obvious until much later.
• ✅ All 10 episodes dropped at once, so there’s no need to pace yourself around a weekly release schedule.
• ✅ If you’ve seen other identity-theft thrillers, resist assuming this one plays the twist the same way — it doesn’t.

The Part That Confuses First-Time Watchers

The biggest mix-up: assuming “the Rat” refers to a single fixed character throughout the show. The label shifts meaning once the finale reframes who’s actually doing the hunting versus who’s being hunted.

The second: expecting a clean, evidence-based resolution. The show deliberately withholds a body and hard proof, which is the point — it’s building toward moral guilt rather than legal consequence.

A quieter one: treating No-ja as comic relief because of the loan-shark framing early on. By the finale, he’s paid a real physical cost for getting involved.

FAQ

Who is the Rat in Mousetrap?

The label shifts by the finale. Je Moon-jae, played by Ryu Jun-yeol, is revealed to be Park Chan-u, a man who stole his own brother’s identity years before the story starts, while Yu Min is the present-day figure hunting him.

How many episodes does Mousetrap have?

Mousetrap has 10 episodes, each roughly 50 minutes long, and all of them were released at once on August 28, 2026.

Is Mousetrap based on a webtoon?

Yes. Mousetrap is a live-action adaptation of the Korean webtoon Field Mouse.

Sources

• Netflix Tudum: Top 10 Non-English TV Shows
• KDramaWorlds: Mousetrap Episode Guide, Cast & Ending Explained
• Fiction Horizon: Mousetrap Recap and Ending Explained

Fact-checked based on public sources as of August 31, 2026.