Directed by

Sung-su Kim
Made by

CJ Entertainment
See current US streaming, rental, and purchase options for Flu (2013) via JustWatch.
Read the complete plot summary and ending explained for Flu (2013). From turning points to emotional moments, uncover what really happened and why it matters.
A tense outbreak thriller unfolds in Seoul as two smugglers, Ju Byung-woo and Ju Byung-ki, stumble upon a grim loss at sea when a shipping container carries illegal immigrants who die from an unknown illness. They seize the lone survivor, Monssai, and film the bodies to show their boss in Bundang, but Byung-woo falls ill and Monssai manages to escape. In a rush, the brothers rush to a clinic, and the contagion spreads as the virus moves through the staff and other patients, signaling the beginning of a citywide crisis.
At the Contagion Center in Bundang, Dr. Kim In-hae faces authority after losing crucial data when her car tumbled into a mine shaft the day before. Her bag is recovered by emergency response team members Oh Ji-goo and Bae Kyung-ub, and Ji-goo hands the bag to In-hae’s daughter Mi-reu after answering a call. As Byung-woo’s condition deteriorates, he begins vomiting blood, forcing his brother to rush him to the emergency room where the pair confront an unknown flu together. Byung-woo dies, and Byung-ki’s desperate pursuit of his brother puts hospital staff in harm’s way as he resists questions about the container.
The following day, an expanding wave of symptoms prompts a coordinated response with the KCDC. The hospital staff incinerate the shipping container, hoping to halt the source, but the disease has already spread: rats that fed on the contaminated remains escape into the city, spreading the mutated virus. The medical team determines the culprit to be a highly aggressive variant of H5N1 that can kill within 36 hours, triggering a formal quarantine of the city.
Monssai finds a chance to intervene when he saves Mi-reu from being struck by a car, all the while aware that his presence could accelerate transmission. Mi-reu reaches out to Ji-goo for help tracking the sick man, but their search yields little. Rumors swirl, panic spreads, and Ji-goo’s efforts to protect others intensify as he saves a woman from an escalator, only to lose sight of Mi-reu in the crowd.
In Bundang, officials are slow to acknowledge the need for quarantine, and the situation rapidly deteriorates as people collapse in the streets. The healthcare system and communications networks strain under the load, and the quarantine is officially implemented. Politicians and administrators pull back to Seoul to brief the Prime Minister, whose public address inflames fear rather than soothe it.
In-hae stays behind in Bundang and teams up with Ji-goo to find Mi-reu. They eventually locate her in a looted supermarket where symptoms are visible and riot police struggle to restore order. The trio fights their way to a path toward Seoul, but Mi-reu’s symptoms threaten their escape when passage is denied. They finally glimpse a way out, only to see Mi-reu’s condition worsen and the window for departure close.
That night, a heavy quarantine is reinforced by the military, allied forces, and health authorities. The population is moved to a camp outside the Tancheon Sports Complex, while those showing symptoms are confined to an infected quarantine zone beneath the stadium to receive care. In-hae hatches a plan to shield Mi-reu, slipping her through examinations and keeping her mask in place to prevent further contagion. In the IQZ, Monssai is discovered, and a proposed direct antibody transfusion for a patient is rejected, which pushes In-hae to take a more personal route by secretly beginning a transfusion for Mi-reu. Her attempts become more urgent as Mi-reu’s condition worsens and she is ultimately moved to the IQZ for treatment.
Conditions inside the camp breed unease: communications are cut, living standards deteriorate, guards in gas masks patrol, gunfire is used to deter birds from spreading the disease, and rumors circulate that the infected are being killed. Pressure from WHO representative Leo Snyder and political leaders forces the president to abandon a pledge to release the uninfected after 48 hours, sparking clashes. When an infected soldier is shot dead, the mob erupts, and Ji-goo is seen rescuing Mi-reu from a pile of burning bodies that are being destroyed as a precaution.
As In-hae and the medical team flee the chaos, Byung-ki executes a suicidal attack to avenge his brother, killing Monssai in the process. Mi-reu begins to recover, and Ji-goo escorts her toward the highway to reunite with In-hae. But Gook-hwan, an infected agitator, leads the mob toward the highway and opens fire, triggering a fierce exchange between the rebels and the soldiers.
Ji-goo hides Mi-reu, who nonetheless makes a full recovery. Gook-hwan’s desperate bid to transfuse Mi-reu’s blood is thwarted when Kyung-ub intervenes, and the insurgent is killed in the scuffle. As Mi-reu escapes to the front of the mob, the confrontation on the highway intensifies. In-hae is wounded while attempting to prevent Mi-reu from crossing the containment line, but Mi-reu shields her mother, and the crowd answers her plea with protective solidarity. The president orders the soldiers to stand down, and Snyder is forced to cancel an air strike. In a hopeful turn, Mi-reu is sent to Seoul to help in vaccine development while medical teams are mobilized to Bundang, signaling a fragile step toward containment after a harrowing outbreak.
Follow the complete movie timeline of Flu (2013) with every major event in chronological order. Great for understanding complex plots and story progression.
Discovery of dead immigrants and survivor
Smugglers Ju Byung-woo and Ju Byung-ki discover that illegal immigrants died in a shipping container from an unknown illness. They capture the sole survivor, Monssai, and bring a cellphone video of the bodies to their boss. Byung-woo grows sick, and Monssai manages to escape.
Fractured questioning and initial outbreak
The brothers take the survivor to a clinic where Byung-ki is questioned about the container. The contagion spreads as the virus mutates, and hospital staff begin to fall ill. Byung-woo dies, and Byung-ki refuses to answer questions about the container.
In-hae reviews evidence
Dr. Kim In-hae at the Contagion Center reviews the cellphone video and theorizes that conditions in the shipping container allowed the virus to mutate. She is reprimanded for losing important data after her car fell into a mine shaft the day before.
Bag retrieved and family link established
Oh Ji-goo and Bae Kyung-ub retrieve In-hae's bag from a mine shaft and deliver it to In-hae's daughter Mi-reu. The personal connection spurs In-hae to monitor the outbreak more closely and to share her early suspicions about the virus.
Byung-woo dies and hospital tension
Byung-woo's condition worsens and he is taken to an emergency room where he is isolated with an unknown flu. Byung-ki coerces hospital staff and refuses to answer questions about the shipping container, driving the tension within the hospital.
Shipping container incident escalates
The next day, many people show pronounced symptoms as the outbreak spreads. Hospital staff and the KCDC incinerate the shipping container, but rats feeding on the corpses escape into the city, spreading the contagion further.
Monssai acts and rumors grow
Monssai rescues Mi-reu from being hit by a car, aware he might be spreading the virus. Mi-reu calls Ji-goo to help search for the sick man, but they have no success. Rumors of the outbreak spread and people begin to panic.
Quarantine is imposed amid chaos
Administrators and politicians are pressured to quarantine as hospitals and communications systems become overwhelmed. The Prime Minister makes a public announcement that worsens the panic in Bundang.
Supermarket confrontation and cross-border move blocked
In-hae and Ji-goo search for Mi-reu and find her in a looted supermarket as riot police try to contain the outbreak. They escape before steel shutters come down, but Mi-reu's symptoms prevent passing to Seoul.
IQZ established and secret transfusion begins
Night falls as the Bundang quarantine is reinforced by the army, US forces, and KCDC, and the population is moved to a camp outside the Tancheon Sports Complex with an infected quarantine zone beneath the stadium. In-hae secretly begins a transfusion to Mi-reu after an official decision blocks direct antibody injections.
Mob violence and a tragic confrontation
On the second day, Monssai is found in the isolation zone. Gook-hwan leads an infected mob toward the highway, triggering a gun battle between the mob and soldiers. Byung-ki kills Monssai in a suicidal attack to avenge his brother.
Mi-reu's recovery and vaccine mission
Mi-reu begins to recover and is sheltered by Ji-goo and In-hae as they move toward Seoul. The president orders containment to end and cancels an air strike, changing the crisis's course. Mi-reu is sent to Seoul to help create a vaccine, while relief teams are dispatched to Bundang.
Explore all characters from Flu (2013). Get detailed profiles with their roles, arcs, and key relationships explained.
Ju Byung-woo
A Seoul-based smuggler who uncovers that illegal immigrants died in a shipping container from an unknown illness. He and his brother Byung-ki carry the sole survivor, Monssai, and a cellphone video to their boss, hoping to leverage the incident. His condition worsens as the disease takes hold, and he ultimately dies from the infection.
Ju Byung-ki
Byung-woo's brother who is involved in the cover-up and investigation. He struggles with questions about the container and becomes entangled in efforts to reach his brother. In a final act tied to vengeance, he kills Monssai and meets his end amid the chaos.
Monssai
The sole survivor from the shipping container who carries the potential antibodies. His presence catalyzes the spread of the outbreak and the race to isolate and study him. He is eventually found in the isolation zone and killed by Byung-ki during a desperate bid for vengeance.
Dr. Kim In-hae
A doctor at the Contagion Center who pieces together the mutation theory from a cellphone video. She advocates for experimental treatments and works to shield Mi-reu, navigating bureaucratic resistance. Her interventions with Mi-reu underscore the human stakes of a medical crisis.
Oh Ji-goo
An Emergency Response Team member who retrieves a bag and becomes involved in the pursuit of the sick Monssai and the care of Mi-reu. He relentlessly pursues rescue missions and shows resolve in dangerous, chaotic conditions.
Bae Kyung-ub
An ERT member who assists with the containment and rescue operations. She supports the medical and logistical response, staying close as the situation deteriorates and helping free those trapped in the market and IQZ.
Mi-reu
In-hae's daughter who shows symptoms of the infection but develops antibodies that aid in the fight against the disease. She undergoes protective measures and becomes a focal point in attempts to find a cure, ultimately traveling toward Seoul for vaccine development.
Gook-hwan
An infected man who incites unrest and leads a mob toward the highway where the containment is tested. His actions escalate violence and complicate the evacuation and defense of the city.
Leo Snyder
A WHO official who pressures authorities to release uninfected individuals and coordinates international response. His involvement highlights global scrutiny and the political dimensions of outbreak management.
Learn where and when Flu (2013) takes place. Explore the film’s settings, era, and how they shape the narrative.
Time period
The events unfold in contemporary South Korea, reflecting a modern urban outbreak with advanced medical institutions, media coverage, and international health organizations involved. The story follows the rapid escalation from a local incident to a nationwide crisis, illustrating how urban density accelerates contagion. Government and medical responses shift from initial denial to urgent containment and mass evacuation.
Location
Bundang, Seoul, Tancheon Sports Complex
Bundang serves as the outbreak's initial hub in a modern South Korea setting, with the Contagion Center located there. The city becomes a quarantine battleground as the virus spreads through hospitals, markets, and transit. Seoul later becomes central for care and vaccine efforts as authorities coordinate with international agencies.
Discover the main themes in Flu (2013). Analyze the deeper meanings, emotional layers, and social commentary behind the film.
🦠
Outbreak
A deadly, mutating virus drives the plot from the discovery of deaths in a shipping container to its swift spread through hospitals and city streets. The film emphasizes how quickly contagion can overwhelm urban systems and expose gaps in health surveillance. It highlights the race to identify the pathogen before it kills within 36 hours. The mutated H5N1 strain becomes a constant threat that shapes every decision.
🚧
Containment
Quarantine becomes the central tool, with IQZ beneath stadiums and camps outside cities. The military, health agencies, and politicians clash over strategy while resources and communication falter. Civilians face scarcity, panic, and rioting as trust between authorities and the public fractures. The film probes the ethics and efficacy of forced isolation under extreme pressure.
💉
Treatment
Doctors race to find a remedy, exploring antibodies and transfusions as possible bridges to a cure. In-hae's effort to use Monssai's antibodies on a patient is resisted, revealing tensions between urgency and protocol. The film centers on the stubborn hope that a child’s immune response might unlock a vaccine. It shows improvisation and moral risk in desperate medical settings.
🤝
Humanity
The outbreak strains relationships and reveals acts of courage: rescuers, doctors, and families band together to shield the vulnerable. Riots and fear give way to protective instincts as the state adapts its response and halts drastic measures. The bond between mother and child anchors the story, underscoring resilience amid chaos.

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Explore the mobile appDiscover the spoiler-free summary of Flu (2013). Get a concise overview without any spoilers.
In the quiet suburb of Bundang, just beyond the bustling heart of Seoul, an unseen threat begins to whisper through the streets. A sudden, lethal airborne virus turns everyday life into a race against an invisible clock, turning ordinary neighborhoods into zones of urgent uncertainty. The city’s familiar rhythm is replaced by a palpable tension, as panic and the need for decisive action loom over every decision, setting the stage for a high‑stakes thriller that feels as close to home as the air we breathe.
At the center of the crisis stands Dr. Kim In‑hae, an infectious‑disease specialist whose expertise is matched only by her determination to uncover the mystery behind the outbreak. Partnering with her is Oh Ji‑goo, a seasoned rescue worker whose street‑level experience and calm under pressure provide the vital bridge between medical theory and on‑the‑ground reality. Together they form an unlikely duo, each bringing a different perspective to a problem that demands both scientific rigor and swift, compassionate action.
As officials debate a full‑city quarantine, the pair dives into a labyrinth of clues—tracing the virus’s origin, chasing down leads on a potential serum, and navigating the fragile line between containment and chaos. Their journey weaves through bustling clinics, hurried emergency calls, and the looming presence of a city on the brink, all while the invisible enemy continues to spread. The atmosphere is thick with urgency, a blend of procedural precision and gritty human resilience that keeps the audience on edge.
The film’s tone balances clinical tension with moments of personal resolve, painting a portrait of a community grappling with an existential threat. It asks what it means to protect the many while racing against time, and how ordinary heroes emerge when the world around them collapses into uncertainty. The story promises an immersive, pulse‑pounding exploration of survival, science, and the fragile hope that can arise even in the darkest of outbreaks.
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