4th Period Mystery 2009

Mystery

Thriller

Crime

Action

Box Office

$361K

Runtime

86 mins

Language

Korean

Directed by

Sang-yong Lee

Made by

Sway Entertainment

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4th Period Mystery Plot Summary

Read the complete plot summary and ending explained for 4th Period Mystery (2009). From turning points to emotional moments, uncover what really happened and why it matters.

Jung-hoon, Yoo Seung-ho, is the top student at his school, respected for his quick thinking and calm approach under pressure. His rival, Tae-gyu, Sang-geun Jo, thrives on provocation and uses every chance to undermine him, and the two are known enemies among their peers. One afternoon, Tae-gyu pushes Jung-hoon too far and the latter brandishes a knife in a heated moment, an act witnessed by another student. Jung-hoon walks away, but as the 4th period begins he returns to a grimmer scene: Tae-gyu lies dead, stabbed repeatedly. In shock, Jung-hoon picks up the bloody knife from a nearby desk, just as Lee Da-jeong, Kang So-ra, arrives and catches him in a incriminating position.

Lee Da-jeong believes in Jung-hoon’s innocence and insists on helping him unravel what happened, recognizing that time is against them because in 40 minutes the rest of the class will return and the body will be discovered. The pair team up to search for clues and quickly realize that almost everyone in the room could be a suspect. The investigation unfolds with careful attention to motive and opportunity, while an unseen threat begins to close in on them as well, turning the high school into a tense maze where trust is scarce and danger lurks around every corner. As they dig deeper, the atmosphere grows more claustrophobic, and the stakes rise: catching the real killer becomes not only a matter of clearing Jung-hoon’s name but of staying one step ahead of a killer who has his sights set on them.

4th Period Mystery Timeline

Follow the complete movie timeline of 4th Period Mystery (2009) with every major event in chronological order. Great for understanding complex plots and story progression.

Rivalry erupts and knife threat

In the school, Tae-gyu verbally and physically provokes Jung-hoon, pushing the rivalry to a breaking point. In a moment of panic, Jung-hoon threatens Tae-gyu with a knife, an act that is witnessed by another student. The tension between them marks the start of the deadly sequence.

Afternoon School hallway

Discovery of the murder

Shortly after the threat, at the start of 4th period, Jung-hoon returns to the classroom to find Tae-gyu dead, stabbed repeatedly. The room is smeared with blood, and a bloody knife lies on a nearby desk.

Start of 4th period 4th period classroom

Da-jung believes Jung-hoon's innocence

Da-jung appears in the doorway and witnesses Jung-hoon holding the bloody knife but believes his innocence, offering to help. She pledges to help solve the mystery before the rest of the class discovers the body.

Immediately after discovery 4th period classroom

They team up to investigate

Realizing the urgency, they decide to team up and search for the real killer together. They understand they must act quickly to uncover clues before the class returns.

Following discovery School building

Time constraint looms

With 40 minutes before the class returns and the body will be discovered, they race to collect clues. The ticking clock adds pressure as every moment counts.

40 minutes before class resumes School building

Suspects multiply

As they search, they realize nearly everyone in Tae-gyu's circle could be a suspect. Alibis blur and hidden motives surface, keeping the list of potential culprits long.

School hallways

The killer hunts them

The killer appears to be aware of their investigation and begins pursuing them, turning the halls into a perilous obstacle course. The duo must stay ahead while continuing to search for clues.

School corridors

They press on despite danger

Despite the danger, Da-jung and Jung-hoon continue their search, moving through classrooms and corridors to uncover hidden clues. Their resolve strengthens as they realize the killer is closer than they thought.

School building

A pivotal clue emerges

A crucial clue surfaces that helps narrow down suspects. The revelation sharpens the focus on the real culprit and raises the stakes for the investigation.

Various locations in school

Race against time to reveal the culprit

With the countdown still on, they race to assemble the evidence and expose the real killer before the class inevitably returns. The pressure mounts as the suspect list tightens.

Countdown ends as class returns School corridors

Plan to confront the killer

They devise a plan to confront and capture the murderer, using the clues they've gathered to corner him. Da-jung's belief in Jung-hoon's innocence drives their bold move.

School courtyard

The pursuit continues

The investigation is far from over, and the pursuit continues as they hunt for the truth. The killer remains at large, keeping the stakes high and the tension unresolved.

School

4th Period Mystery Characters

Explore all characters from 4th Period Mystery (2009). Get detailed profiles with their roles, arcs, and key relationships explained.

Han Jung-hoon (Yoo Seung-ho)

A top student whose competitive drive and hot temper push him to the edge during a confrontation with Tae-gyu. He is shocked by Tae-gyu's murder and clutches the bloody knife, creating suspicion but he remains determined to prove his innocence. He relies on Da-jeong's help and shows resilience as the investigation unfolds.

🎭 Rivalry 🧠 Intelligence 🔪 Impulsiveness

Lee Da-jeong (Kang So-ra)

A perceptive and brave classmate who believes Jung-hoon's story and offers to help investigate. She navigates the danger as they search for the real killer, balancing skepticism with loyalty. Her resourcefulness and courage keep the partnership alive under threat.

🤝 Alliance 🧠 Resourcefulness 🛡️ Courage

Kim Tae-gyoo (Kim Tae-gyoo)

The rival who provoked Jung-hoon and looms large as the murder's initial suspect. His relationship with Jung-hoon drives the class rivalry and heightens the stakes once he is found dead. The murder shifts the focus from rivalry to the hunt for the real culprit.

🎭 Rival 🕵️‍♂️ Suspect 💀 Victim

Crazy (Park Cheol-min)

A nickname for a disruptive classmate who adds tension and misdirection to the mystery. He becomes part of the web of suspects as motives and loyalties in the class are revealed. His unpredictable behavior keeps other characters off-balance.

🎭 Classmate 🧭 Misdirection 🕵️‍♂️ Suspicion

4th Period Mystery Settings

Learn where and when 4th Period Mystery (2009) takes place. Explore the film’s settings, era, and how they shape the narrative.

Location

High School, 4th Period Classroom

The events unfold primarily inside a modern high school during the 4th period. The classroom where the murder occurs serves as the central stage and a ticking clock for the investigation. Hallways and common spaces become tense settings as suspects are profiled and the killer hunts Jung-hoon and Da-jeong.

🏫 School 🧭 Mystery

4th Period Mystery Themes

Discover the main themes in 4th Period Mystery (2009). Analyze the deeper meanings, emotional layers, and social commentary behind the film.

🔎

Mystery

A murder within a close-knit school turns the story into a tense investigation where motive and opportunity must be weighed. Clues surface and misdirections arise, forcing characters to question what they think they know about each other. The pressure of a class-wide deadline heightens the urgency as the killer looms nearby.

🤝

Partnership

The alliance between Jung-hoon and Da-jeong becomes essential to clearing his name and identifying the real killer. Their collaboration requires trust, courage, and quick thinking under threat. As danger closes in, their teamwork contrasts with suspicion and rivalry surrounding the class.

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4th Period Mystery Spoiler-Free Summary

Discover the spoiler-free summary of 4th Period Mystery (2009). Get a concise overview without any spoilers.

In a bustling high school where the rhythm of lessons masks an undercurrent of rivalry, Jung‑hoon carries the reputation of being the top student, a crown that draws both admiration and envy. His most persistent challenger is Tae‑gyu, a classmate whose provocations blur the line between playful competition and dangerous confrontation. The ordinary chatter of lockers and chalkboards is suddenly pierced by an unmistakable silence as the school moves into the fourth period, a time that will prove far more consequential than any test.

When the bell rings, Da‑jung rushes into the classroom to find Tae‑gyu motionless, the scene frozen in a tableau of shock. The discovery places Jung‑hoon in a compromising position, his hands still trembling from the recent encounter. Rather than condemn him, Da‑jung offers a lifeline: a pact to uncover the truth before the remaining students flood back and the secret is exposed. Together they are thrust into a frantic sprint against a 40‑minute deadline, navigating corridors that feel both familiar and eerily labyrinthine as the clock ticks louder with each passing second.

The film folds its tension into the very fabric of the school day, turning ordinary hallways into shadowed passages where every glance could hide a clue. Mood swings between the frantic urgency of a race‑against‑time thriller and the intimate, almost whispered anxieties of teenage distrust. As Jung‑hoon and Da‑jung delve deeper, the atmosphere crackles with the possibility that anyone could be the hidden hand behind the crisis, while the looming return of their classmates adds a palpable pressure. In this tightly wound setting, the story explores how quickly alliances can shift, how fear can ignite cooperation, and how a single period can become a crucible for truth and survival.

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