The Great Flood Explained: Plot Breakdown, Ending, Review

What is The Great Flood acting out?

The Great Flood is basically a story about "apocalyptic flood + high-rise survival + secret mission".

In the near future, a catastrophe triggers a global flood (in the film, it's linked to a celestial collision and the melting of Antarctic ice), submerging vast areas of the Earth's surface. In a high-rise apartment building in Seoul, AI scientist Gu An-na is trapped with her young son, Ja-in. As the water level rises, they can only escape to higher floors, facing challenges such as oxygen deprivation, blocked passageways, panicked crowds, and the collapse of resources. Meanwhile, Hee-jo (played by Park Hae-soo) appears and intervenes in the rescue, but his "rescue" is not simply a heroic act: Anna is being targeted because she is involved in a secret plan concerning the survival of humanity. So the first half of the film looks like a pure disaster survival story, while the second half gradually reveals the science fiction storyline of "why they had to take her away and what other purpose there was behind this disaster", turning survival into a tug-of-war between mission and ethics.

The Great Flood Cast: Main Cast List

1. Kim Da-mi | Gu An-na, an AI scientist and mother who escapes with her child from a flooded apartment; the film's emotional core and survival decisions revolve around her. IG: @d_a___m_i

   
   

2. Park Hae-soo plays Son Hee-jo, a key figure in the "escort/evacuation" of Anna. His role lies between rescuer and executor, and he also drives the revelation of the truth later on. IG: @haesoopark_official

   
   

3. Kwon Eun-seong | Plays Ja-in (also known as Za-in in some sources), Anna's child and the most important emotional anchor in the plot (and a key variable in the "test/mission"). IG: @kwonesung

   
   

4. Jeon Hye-jin | Plays Lim Hyeon-mo, one of the key figures closely connected to Anna's plan/system (an important character from the "system's" perspective). IG: @jeonhaejinii

   
   

5. Park Byung-eun plays Lee Hwi-so, a key figure in the "Action/Order" faction (particularly the execution route). Instagram: @byung_eun_park

   
   

6. Lee Hak-joo | Plays Shin Ga-won, a key supporting character connected to the events (influencing information and choices). IG: @imcokecolor

   
   

7. Kang Bin | Plays one of the supporting characters, Mi-jung; some sources describe him as a "plunderer/opportunist" amidst the chaos. IG: @kangbin.official

   
   

8. Jeon Yu-na | Plays Lee Ji-soo, one of the supporting characters in the film; her character arc involves the protagonist's choices during disaster scenes. IG: @yuna110718 (Account managed by family according to her own description)

   
   

9. Kim Dong-yeong | (Listed on Netflix; some information is categorized under supporting roles in ensemble dramas such as "The Predators") IG: @yagobo_

The Great Flood Plot

(I) The Beginning of the Story:

A near-future escape from a Seoul skyscraper: An astronomical catastrophe triggers global flooding, inundating vast swathes of land, including Seoul. AI scientist An-na and her young son Ja-in are trapped in their high-rise apartment as the water level rises, leaving only upwards as their only escape route. An-na tries to comfort her child while navigating the chaotic floors and increasingly flooded passageways. The first half of the story is driven by the suffocating tension of disaster survival.

(II) The crucial moment:

During the escape mission led by Park Hae-soo's character, Son Hee-jo, Anna encounters him. He claims that a rescue helicopter will arrive on the rooftop and reveals a more cruel truth: Anna was involved in the "AI Emotion Engine" research, and her former colleague has disappeared or may be dead, making Anna the only key figure who can continue the project. In other words, the rescue operation is not just about saving "people," but more like taking away "those who must survive."

(III) Mid-section transition:

During their journey to the rooftop, Jae-in and Anna were briefly separated. Anna nearly drowned while searching for her son, triggering memories of past traumas. She also failed to rescue a child trapped in an elevator. When she finally found Jae-in, his condition had worsened due to the missing medication. Anna was forced to scavenge for resources and make makeshift treatments between floors to keep him alive. These events gradually made Anna realize that the so-called "rescue" might not include her son, and that some people had implicitly agreed from the beginning that "as long as Anna lives, that's enough."

(iv) Rooftop High Tide:

The mother and child were forcibly separated. When they finally reached the rooftop, armed rescue personnel took control of the situation, subduing In-ri and restricting his movements; Anna was forced to board a helicopter. In a state of extreme distress, Anna could only promise, "I will come back," but after the helicopter took off, she also witnessed the rescue team using some kind of "procedure/device" to treat the child, suggesting that the true purpose behind this was far more ruthless than disaster relief.

(V) The truth is revealed:

The flood is actually a virtual simulation test helicopter for the "Emotion Engine." On the helicopter, Anna is told that a greater apocalypse is approaching: Earth will become uninhabitable due to subsequent celestial impacts, and humanity is attempting to "rebuild humanity" artificially, even advancing the development of fertile artificial life forms, but "emotions" can never fill the gap. Therefore, the entire "Flood Apartment" is actually a virtual simulation used to test whether a mother can successfully save her child in extreme conditions, thereby calibrating and perfecting the Emotion Engine.

(vi) Ending:

The film loops through time until Anna makes the choice that "truly saves her child." She is then sent back to the simulation system, and the story restarts with her "reawakening." In each replay, she begins to make different choices: not only mastering the escape route faster, but also helping those she previously ignored, and more forcefully resisting the "system's" attempt to separate her from her child. In the final iteration, pursuers and giant waves simultaneously approach the rooftop. Jae-in jumps into the water, causing the simulation world to collapse and distort. Anna breaks free and jumps after her, reuniting mother and child in the churning water. The film concludes with Anna and Jae-in in a spaceship, heading towards Earth, implying a successful test, the key answer to the emotion engine being found, and the human reconstruction plan being able to move forward.

The Great Flood's role relationship

The core trio

1. Gu An-na (Kim Da-mi) ↔ Shin Za-in/Ja-in (Kwon Eun-sung): Mother and son. The core of the film's plot revolves around An-na's struggle to survive in the flood and then find her son.

2. Gu An-na ↔ Son Hee-jo (Park Hae-soo): Hee-jo rescues An-na and helps her find the lost child; however, his assistance is "mission-oriented" and his motives are not entirely benevolent, a fact that An-na quickly realizes.

3. Son Hee-jo ↔ Ja-in: On the surface, he helps Anna find her child and evacuate to the roof together; in reality, he is tied to the rescue/security system that "takes Anna away", so there is a natural tension and distrust between him and the child.

Rescue/Security Team (Characters on the same side as Hee-jo)

4) Hee-jo: AsianWiki explicitly states that he belonged to the "human resource security team" and his purpose was to take Anna away from the disaster.

5) Security team leader (Lee Joon-hyuk): A security team member who is responsible for on-site operations (more focused on "catching people/controlling the situation"), and one of the sources of conflict with the protagonist's storyline.

Apartment Trapped Residents / Ensemble Story (People the Protagonist Encounters Along the Way)

6) #1503 Pregnant Woman (Eun Su) + #1503 Man (Ahn Hyun-ho): The trapped resident branch, whose function is to amplify the moral choices and human tension in the disaster.

7) Grandpa #2002 (Lee Dong-chan), resident of #702 (Jo Seung-yeon), and deaconess/church person (deaconess, Park Ji-won): They all belong to the "building resident group portrait" and represent different types of survival choices and the collapse of order.

8) Anna's mother (Park Mi-hyun): Anna's family relationships are crucial to the character's background (and also affect her emotional state).

Opportunists/plunderers (external conflicts that directly threaten the protagonist)

9) Mi-jung (Kang Bin) + another looter (Kim Dong-yeong): labeled as a looter, she is one of the most realistic violent obstacles to the protagonist's "escape upwards".

Main named characters (listed in the public roster, but the descriptions don't go into much detail about their relationships)

10) Im Hyeon-mo (Jeon Hye-jin), Lee Hwi-so (Park Byung-eun), Shin Ga-won (Lee Hak-joo), and Lee Ji-su (Jeon Yoo-na): They are listed as main characters in the publicly released cast/role list, but the official introductions do not clearly state the direct relationship like "Anna-Hee-jo-Jae-in". You can first regard them as key figures who connect to the "security/mission line" and the "apartment group line" respectively.

Analysis of the ending of The Great Flood

The following is an analysis of the ending of "The Great Flood" (대홍수/The Great Flood), which will directly explain the "truth" and symbolic meaning of the last paragraph. Please read this as a full spoiler.

The film deliberately heightens the audience's emotions at the moment when they are "almost rescued" on the rooftop: Anna (Gu An-na) finally manages to climb to the roof with her son Ja-in, only to discover that the rescuers' real priority is not "mother and child to live together," but "ensuring Anna is taken away." The film explicitly shows rescuers restricting Ja-in, forcing Anna to board the plane, and even using some kind of device on the child. This action is the key foreshadowing of the ending twist: what you think is the cruel reality of a disaster film is actually a system executing a "program."

Then, the truth is revealed from the helicopter: the flood and high-rise survival scenario is not a single, real-world event, but a "virtual simulation." The purpose of the simulation is to test an emotion engine called the Emotion Engine—it needs to demonstrate "what a mother would do to save her child in extreme circumstances," extracting this emotional response into replicable and calibrable data to support the "Humanity Sustainability Project." In other words, Anna was listed as a must-rescue candidate because she was tied to the project itself; Ren, on the other hand, was more like part of the test questions than a "person" on the rescue list.

The real ending isn't "escaping," but "running back to success." Anna is sent back to the simulation, reliving the same day, the same building, and the same process, but she begins to make different choices: no longer just concerned with the survival of herself and her child, but making up for the indifference and oversights of the first iteration. For example, she tries to rescue a child in an elevator and helps a woman in labor. This isn't simply about making the protagonist kinder, but about using narrative language to tell you that the emotional engine doesn't need "survival skills," but rather "calibrable emotional response curves"—the more Anna acts like a "human" each time, the closer the system gets to the answer it wants.

The climax of the final iteration occurred during a scenario where a giant wave (tsunami) approached and armed personnel were pursuing them. Ren jumped into the water, and the simulation began to distort and collapse. Anna broke free and jumped in after him, reuniting mother and child in water where survival seemed impossible. This "jump" is crucial: superficially, it represents a mother's selfless act for her child; structurally, it also symbolizes Anna's refusal to be taken away again and her rejection of the path the system had laid out for her. She wasn't rescued from the scene; instead, she chose to push the outcome to a point where the system could no longer control it with the pre-defined script, forcing the test to complete.

The spaceship shot at the end of the film often leaves viewers confused: why "heading towards Earth" instead of "leaving Earth"? Based on the information provided in the film, it hints at two things: first, the simulation was finally deemed successful, and the emotional engine received crucial corrections; second, Anna and Zai Ren have been incorporated into the "Humanity Continuation Project" vehicle (or new civilization vehicle), thus returning to a place where they are needed as "preserved samples/reconstructed lives." The film doesn't definitively state whether they are original humans, clones, or some kind of human-machine hybrid, which leaves a lingering impression on the audience: when emotions are engineered, are humans still human?

If you find the ending "gloomy," it's actually intentional on the director's part: on one hand, it uses the mother-son relationship to move you to tears, and on the other hand, it turns those tears into an uncomfortable self-doubt by saying "all of this is actually a replay script used to calibrate emotions." British media reviews point out that after shifting from a disaster film to a "virtual loop," it seems to be discussing a darker theme: emotional responses are calibrated, entertainment content is like an algorithmic collage, and the audience's emotions may also be designed and optimized.

To sum it up in one sentence: the ending of this film doesn't simply say "motherly love saves the world," but rather asks, "When the world treats motherly love as a quantifiable engine, can motherly love still be considered a free choice?" Anna's final jump is her answer to this question.

The Great Flood's film review:

If you had to describe The Great Flood in one sentence, it would be this: it's a film that crams the "adrenaline rush of a disaster movie" and the "coldness of science fiction" into the same container. The first half will make you want to watch it all in one go, but the second half will force you to make a choice—either accept its conceptual ambition or lose patience with the narrative pace.

What I love most is its spatial design. Confining the flood to a vertical maze of "escaping upwards through high-rises" naturally creates a sense of urgency, like a countdown: the water doesn't spread horizontally, but rather engulfs your escape route layer by layer; each change of floor feels like a new level, easily compelling the audience to "calculate routes, time, and risks" alongside the protagonist. This design is actually very clever because it makes the disaster not just a backdrop, but the engine that drives the plot forward.

In terms of performance, Kim Da-mi carried the emotional curve of the entire film. She didn't portray a single emotion, but rather "a mother's dynamic system under pressure": fear, anger, guilt, rational calculation, collapse and then getting back up. These transitions could easily become empty slogans without believable physical responses, but her presentation had weight. Park Hae-soo's character, on the other hand, was effective in another way: he didn't necessarily make you like him; he wanted to make you uncertain, to make you doubt him every time you wanted to believe him. This sense of unease greatly enhanced the later twist.

However, the film's problem lies precisely in the transition after its initial "effectiveness." The shift from disaster survival to a larger science fiction setting is not smooth enough, creating a psychological gap for the audience: you're initially invested in "I just want them to survive," but then suddenly you're required to "understand an entire system and proposition." If the information is revealed in a rather abrupt way, the pacing breaks down. It's not that the concept is bad, but rather that the "delivery of the concept" feels more like a discourse than a drama. In other words, while the latter part tries to deepen, the way it goes feels like being pulled to the front of a lecture.

I also think its emotional manipulation is a bit contradictory: it wants to criticize the "engineering, testing, and optimization of emotions," but at the same time, it uses very traditional disaster film techniques to make your heart race and your eyes water. This is not necessarily a flaw, and may even be a deliberate irony—you are being manipulated by emotions on one hand, and on the other hand, you are told that you are being manipulated—it just doesn't handle this tension very well, so some people find it interesting, while others feel like they've been tricked.

Overall, *The Great Flood* isn't the kind of disaster film that's neat, comfortable, and easy to put down after watching; it's more like a narrative shell of an "emotional experiment." If you enjoy the first half's confined space disaster survival, it will provide you with plenty of cinematic stimulation; if you're also willing to accept the science fiction themes in the second half, you'll get a chilling, unsettling aftertaste. Conversely, if you're looking for a purely enjoyable escape film, or if you want a more natural and less didactic twist, you might find that it doesn't quite blend the two film styles together smoothly.

My assessment of it would be "ambitious, daring to take unexpected turns, strong in the first half, but requiring more precise narrative techniques in the second half." It's worth watching, but not everyone will like it.