Colony

We open to scientist Dr. Seo Young-Chul (Koo Kyo-hawn) in his lab. He calls the police and tells them he plans to commit an act of bioterrorism, where he himself is the only vaccine. We see him inject a compound into his arm, the supposed antidote to his virus.

At the Dongwoo-ri Building, a conference for Chains Bio is taking place. Kwon Se-jeong (Jun Ji-hyun) is met by her ex-husband Han Gyu-Seong (Go Soo) who hopes to introduce her to the CEO of Chains Bio, Kang Woo-Chul, in order to get her a job. Kwon had previously worked as a professor before she was fired after exposing a fellow professor of abusing grad students. Kwon and Han have been divorced for ten years, and Kwon asks Han why he is working so hard to get her a job. Han tells her he is trying to help and that “she has no friends.”

The two listen to Kang speak, as he notes the power of collective intelligence, akin to ants and yellow slime mold. If they could harness that for human use, a new evolution in humanity could occur.

Kwon looks at her invitation, which had a special message attached: “Imperfect communication is the source of all tragedy.”

Kang then shows that through their research they were able to make a paralyzed rat walk again, once again underlying the potential of the science.

Outside in the lobby of the building, Security officer Choi Hyun-Seok (Ji Chang-wook) is spending his lunch hour with his older sister Choi Hyun-Yee (Kim Shin-rok). Hyun-Yee is paralyzed and uses a powered wheelchair to get around. They go inside one store, and see camping equipment. Hyun-Yee suggests that the two of them should go camping. Hyun-Seok is surprised but agrees, so Hyun-Yee goes to buy some camping stuff.

As Kang finishes up his speech he sees Seo at the back of the room, which makes him pause. Kwon and Han go up to him to introduce her when Kang gets a call from the police about Seo and his apparent bio weapon attack. Excusing himself, he tells the police he may have seen Seo but he cannot be sure. Han tells Kwon to go after Kang and try and make an impression.

Going to a VIP bathroom area, Kang is confronted by Seo, which Kwon sees from a distance. Seo berates him for stealing his research. Kang calls him psychotic and that his research was unusable and unethical as it could lead to human extinction (having obviously fired him for his instability). Seo tells him it is not extinction but a rebirth, noting that collective thought eliminates troublesome individuality that creates the world’s problems. As Kang goes to leave, Seo injects him with the virus. Kang throws Seo into a room and barricades the door. As he tries to call for help, Kang begins to violently vomit slime mold, fully turning into a zombie. As his body begins to twist and contort, three men nearby see him and stop, transfixed by what is happening. Kang charges at them and leaps, latching onto one man and tearing out his throat. The infection has begun…

A trio of police officers led by Officer Lee arrives at the building to warn them about the threat. Suddenly, they begin to hear screams and more infected people attack his officers. Lee calls for the entire building to be on lockdown.

Meanwhile, Kwon and Han go to dinner before they leave. Han takes a call from his wife and daughter. His wife Gong Seol-hee (Shin Hyun-been) asks where his passport is and he tells her before telling them both he will be home soon. When Kwon asks about his passport, he tells her he accepted a job in California and they may move there permanently. Kwon retorts that is why he wanted to help her get a job so bad; so she would be taken care of before he leaves for good. Kwon asks him again why he even married her. Han pauses for a moment and tells her he loved how she never backed down and fought for what she thought was right. Kwon scoffs, noting all the times he told her to stop doing that. Han replies that he did genuinely love that about her but he couldn’t keep up with her righteousness; noting he is a bit of a coward. The two pay their bill and head out to leave.

Shortly after, three teens arrive at the restaurant where one of the teens, So-eun, is being bullied and manipulated by the older male and female students who force her to pay for all their food.

Hyun-Seok hears the lockdown order over his radio but it is garbled and he does not understand it.

As Hyun-Yee is leaving the building, she, along with Kwon and Han hear the commotion as the infected continue to pounce on new victims. The chaos causes a stampede and Hyun-Yee is knocked out of her wheelchair, with Kwon and Han helping her up. The three, along with Hyun-Seok, Lee, and the camping store owner lock themselves into the store. Kwon watches as the zombies crawl around the floor, not knowing how to walk. The zombies begin to attack the glass of the store until Kwon turns out the light. Unable to see them, the horde stops their attack.

However, they see the reflection of the restaurant where So-eun, the two other teens, and the restaurant staff are, and begin to attack there. In an instant, all the infected raise their heads as if in a trance. Getting new information, they create a coordinated attack against the restaurant. Realizing they will be killed soon, Kwon is able to send a message to So-eun who turns out the lights. However, there is still a powered up video poster of a man, and since the zombies cannot tell the difference, begin to attack, which impacts the glass.

Trying to think of a way to save the people, Hyun-Yee suggests using her wheelchair and cardboard cutouts of people to lure them away. Using the sound of the wheelchair and the cut outs, they lure the zombies away from the restaurant to let them cross over to the other store. While the rest of the group is terrified, So-eun eagerly crosses over, followed by the male teen and the two restaurant staffers. The older teenage girl, completely frightened, refuses to come over, so Han volunteers to get her. Convincing her to leave, they almost make it across when a zombie finds them. Han pushes her out of the way so she can get in safely and begins to dodge the zombie trying to bite him.

Meanwhile, the zombies who had been trying to “eat” the cutouts are given a new collective update of information that posters and cutouts are not people and not food; in addition, they are now able to stand and walk. Han tries to race for the door but is tackled, his phone flying into the store, and the group can only watch as he is killed. Kwon sees Han’s phone ringing; his wife is calling him.

The police and the government arrive, locking the building down and barricading it off.

Han’s phone calls again and this time Kwon answers, to see Han’s daughter on the face time call. The young girl is obviously confused why her father isn’t there and has to be ushered out of the room by her grandmother. When Gong asks Kwon what happened, Kwon tells her that Han saved some people. When Gong asks what happened after, Kwon doesn’t answer, inadvertently giving Gong the worst news of her life; that she is now a widow.

As the group debates how they will be rescued, Lee tells them that no help is coming as the building is under lockdown and unless they find Seo, who claims to have the vaccine. Kwon realizes she saw Seo with Kang and that was on the third floor, which they need to access via an elevator.

The group argues how they will get past the horde. Kwon notes that they must be sharing collective intelligence much like ants and they can use that to their advantage. Explaining that sometimes collective information loops can be sabotaged such as with a circular ant hill or giving the hive mind false information. When one of them asks how they can trick the horde to not attack them, Kwon has an idea.

Dousing one of the restaurant workers in perfume they will trick the zombies into thinking that is how humans smell. Then they will spray themselves down with a different scent to mask themselves and buy time. The man goes out and lures the zombies away, stealing more of the same perfume before returning. The group set a trail of perfume to the back room while they coat themselves in antifreeze. Letting the zombies in, they are undetected. The group, along with Hyun-Seok who is carrying his sister in a steel backpack (as she cannot walk) leave the store and head to the elevator.

Along the way, the older teenage girl smacks into some zombies and becomes trapped under their weight. The infected discover the ruse and begin to charge them, forcing Hyun-Seok to fight some. Running out of time, Kwon asks for a lighter and sets off the sprinklers, dulling the infected sense of smell, allowing them all to get to the elevator.

Gong, a fellow scientist herself, drives to an unknown location, listening to a news report blaming Seo for the outbreak and how his father, a university professor, committed suicide when he fell under scandal. The newscasters wonder if the attack is a personal one due to that.

Kwon’s group get to the third floor and find Seo who lets himself be cuffed by Lee. Lee tells the group they need to make it to the roof to hand over Seo and be rescued. Hyun-Seok tells them of a little-known cargo elevator that can take them there.

Gong arrives at her destination and meets with her team. They have found Seo’s lab that he built after being fired.

As the group goes to the 30th floor, Seo commends the one man for his footwork during the perfume distraction and then quickly hits the button for the 9th floor. The doors open, where countless infected wait. The horde attacks the group, killing the older male teen and the two restaurant workers. Kwon watches as the others beat back the horde and notices Seo can easily walk through the infected without being attacked.

Closing the door, they make it to the 30th floor only to find it full of infected too. Needing to find a safe path, they ask Hyun-Seok where the control room is. He tells them B2.

Back at Seo’s lab, Gong and several military men enter, finding dozens of monkeys in glass cages. Noticing one has broken out, it begins to attack the group, which causes the others to break out and attack. The first one corners Gong only to be shot dead by one of the men, leading the others to stand frozen in place. Gong sees a poster board with pictures of the monkeys all linked to the one that was just killed.

Back at the building, on level B2, the group find themselves in a parking garage. They see that the new evolution is causing multiple infected to mesh themselves together in a grotesque blob. As they dart between cars, the older female teenager crushes a can, making a noise. One of the meshed zombies peels away upside down to look underneath the cars, seeing only the can. So-eun has held the girl’s feet up and tells her to get a grip on herself fast.

Getting into the control room, they begin to look for Seo so they can capture him. Realizing he asked one of the men about something he couldn’t have seen, Kwon concludes he is somehow linked to the horde, being able to see and hear what they do. They watch as Seo meets up with the infected Kang and allows him to bite him. They see that the zombies have their heads raised in an information upload. The group decides to go and capture Seo while they still can while Hyun-Yee volunteers to stay and watch the cameras and get them a clear path.

The group goes and finds Seo. About the time they do, the infected horde regains sentience and tries to attack. Getting into a room, they see a zombie turn around towards them. Kwon realizes that Seo can direct them by what he sees, so they blindfold him so he cannot direct them. Kwon tells the group they also need to communicate by group text so Seo cannot use any information to his benefit.

Hyun-Yee directs them down a safe path that leads into a kitchen area. As the camping store owner asks why they are backtracking, Hyun-Seok says they are going back for his sister. Lee is against this, saying getting Seo and his vaccine out is the top priority, even above their lives. Lee lets her location slip so Seo relays the information to the horde that begins to head there. Seeing no one will help, Hyun-Seok goes alone. Kwon argues they need to help him but Lee pulls a gun. Kwon disarms him and tells him they will wait until Hyun-Seok is back but the camping store owner disarms her in turn. Lee takes his gun back and makes it clear his way stands and she is going to lead them to safety if she wants to live. Kwon has no choice but to follow him.

Hyun-Yee begins to direct her brother as the zombies begin to attack the glass of the control room. When Hyun-Seok realizes she sent him to an elevator with no means to get to her floor, Hyun-Yee tells him she did it on purpose so he could rejoin the group and live, knowing he won’t have time to save her, especially alone. Hyun-Seok pleads with her to let him help her. Hyun-Yee, tears in her eyes, tells her brother that they should have gone camping the week before. The horde breaks into the room and tears her to pieces. Hyun-Seok collapses to the ground in tears.

Kwon and the group look at their phones, having gotten a text. Hyun-Seok holds them ALL responsible for the death of his sister and plans on killing Seo and making sure none of them escape.

Outside in the government HQ, Gong meets with the Prime Minister and relays her findings on Seo’s lab. Given what she found, she concludes that those infected are basically brain dead and cannot be saved, meaning they will all have to be killed to quell the outbreak. The minister is hesitant to make such an order but if a scientist who has lost her husband to the outbreak (i.e. Gong) it would make the news go down easier for everyone. Gong agrees to make the statement and tells them her theory; that if they kill the first person infected by Seo it will stop all the others.

Hyun-Seok tapes up his arms and grabs a large kitchen knife. Going into a hallway, he proceeds to kill every zombie in his path.

The police go through all the footage to find Patient Zero. They ultimately realize that CEO Kang was the first one infected.

Going into a control room, Hyun-Seok finds the group and telegraphs their location over the loudspeaker, allowing Seo to tell the horde where they are. The group is now split in two; Kwon, the two girls, and Seo while Lee uses the camping store owner as a human sacrifice. However, this ultimately backfires on him as he is grabbed by the man, and they are both cornered and devoured.

Finding a storage room to hide in, Kwon tells the girls she will get Lee’s phone so they can contact the rescue team. She tells them to watch Seo. Unbeknownst to them, Seo has learned how to decipher text taps and can understand what is being communicated and sends the zombies after Kwon.

In the storage room, So-eun tells the other girl who is panicking, to calm down, and that Kwon will come back for them. When the girl asks why she is so calm, So-eun says everything they are facing is nothing compared to being bullied by her and her friends. The older girl tries to apologize, but So-eun tells her if she is truly remorseful, she should do it properly after they survive this mess.

Kwon gets Lee’s phone and calls his superior and tells them their location. As she turns to leave, a zombie that appeared dead was not and heard the conversation, which allowed Seo to hear it.

A large SWAT team is dispatched on the roof; half to secure Seo, half to kill Kang and stop the spread. One group of SWAT comes across a literal wall of zombies that rush them. They are able to kill some but are ultimately overrun.

Kwon races back to the storage room with Hyun-Seok behind her.

At the storage room, the older girl hears voices, claiming to be the rescue team. She opens the door to find zombies being able to mimic human voices. They attack the two girls, and the older girl pushes So-eun into the path of a zombie that bites her, only to get trapped herself. Seo stands up and looks at her with utter disdain for her selfish cowardice and mocks her, saying she should apologize to So-eun face to face. The zombiefied So-eun turns on the older girl, killing her as Seo walks off.

The second SWAT team finds Kang and after some difficulty, kills him. Yet, the zombies continue to move. The plan failed and the team is ultimately killed by the horde. Gong realizes Seo is the true patient zero controlling everything.

In a laundry room, Seo is confronted by Kwon. Hyun-Seok appears, trying to kill him but is stopped by her. Hyun-Seok tries to choke her to death, blaming her for the death of his sister, and doesn’t care about a supposed vaccine; Seo has to die for what he did. His attention is diverted back to Seo, so he lets Kwon go. As he goes to strike, Seo asks him if he wants his greatest wish granted. He pulls back some clothing to show Hyun-Yee now able to walk due to her infection. Hyun-Seok is so startled that Hyun-Yee uses the distraction to stab him to death. Seo mocks Hyun-Yee to Kwon, saying she looks much better now.

Kwon, giving him a death glare, throws her invitation at his feet, realizing he was the one who invited her to the conference to be part of his master plan. Seo says he got the idea from her, and what she did to his father. In flashback, it is revealed that Kwon reported Seo’s father to the university after he apparently misused research data and credit of said data of several students, embezzling funds, though Seo’s father claimed the students agreed to it and were going to share the compensation together. The shame led to his suicide, and most likely led to Kwon’s dismissal from the school.

Kwon, enraged, tells him if he wanted revenge, he should have come after her and not killed all these people. Seo says his plan was not about revenge and his dad’s death had purpose, which happened due to the result of imperfect communication.

By linking everyone’s mind together, he can stop all the flaws of improper communication (leaving out the key detail that he himself retains control, allowing him to reign as a God). Kwon realizes how insane he truly is, and Seo says if she wants to be alone, an “outcast” that is fine by him.

A SWAT team arrives and captures Seo as more zombies attack Kwon. The team leaves her behind. Kwon is able to get into a storage room and barricade herself inside.

Back at HQ, the team celebrates Seo’s capture but Gong is horrified they are going to leave Kwon behind. The Prime Minister chides her for overstepping her authority. Realizing she cannot help her directly, Gong calls Kwon. They discuss what they both realize; Seo is controlling the horde and is the true Patient Zero. If they kill him, they stop everything. Kwon realizes that Seo calling her an outcast was him mocking her; to stop him, she will have to kill him, and face the wrath of the nation for damning all the infected to no chance of a cure.

As Seo is being led by the SWAT team, he asks one if he had ever been shot before. Up ahead a few infected SWAT members fire on the group and eat the rest. Now having an infected SWAT team backing him up, Seo kills the team on the roof and rappels down to the ground. Stealing a police van, Seo has it turned around heads back to the building.

Kwon’s hiding spot is compromised but she is able to sneak by. Finding a jacket that is coated in the slime mold, she is able to bypass the horde and escape the building.

Seo unleashes the horde onto the police barricade, opening gaps to kill the crowd and police. The Prime Minister and his team panic, evacuating themselves and leaving the crowd to their fate.

Kwon heads to the barricade and calls Gong, asking her to look for Seo’s location. Finding it, Kwon steals a car and heads after him, using Gong’s directions. Finding Seo, Kwon tries to run him down but he just directs zombies on her, ultimately causing her to crash the car. Getting out, the jacket protects her from being identified, so Seo tells the horde to attack the jacket and thus attack her. Taking it off, she throws on one of the heads of the infected, and spins him in a circle causing the others to pursue it and it causes an ant hill death spiral like a video she showed the group earlier.

Seo, annoyed that he can no longer force the horde to do his bidding, pushes his way through the circle and removes the jacket from the zombie. This act however, resets the horde to their previous primitive state. Kwon hides under a bus, while the horde, mistaking an advertisement on the bus for humans, pushes Seo with them, pinning him between the bus and a burning car, which catches his arm aflame. He tries to push them away, command them once more, but they no longer listen to him. Getting free, he makes one final lunge at Kwon but she pushes him away and watches as he is engulfed in flames before collapsing to the ground, dead. With his death, the entire zombie horde freezes in place like statues, ending the outbreak.

Kwon calls Gong and asks if all the zombies had stopped, which she confirms. Kwon notes that she will be blamed for killing Seo and taking his supposed vaccine with him, but Gong promises to testify on her behalf to ensure that the government will not use her as a scapegoat. “I’ll face being hated with you,” Gong says. As Kwon walks away, she notes the two of them have a lot of work ahead of them. The camera pans across the infected and ends on the face of a man, who suddenly cries out, implying the freeze of the infected people is perhaps only temporary.