The Villainess is a 2017 South Korean action film directed by Jung Byung-gil, starring Kim Ok-Vin. The film had its world premiere at the 70th Cannes Film Festival in May 2017.
According to the director and writer, the movie was inspired by the European filmLa Femme Nikita (1990), which he had seen at the age of 10
In the opening scene, an unnamed highly skilled, and trained assassin enters a hallway and kills numerous people with her gun and knives before being surrounded by cops and smiling a grim smile.
The assassin is shown in a room in an unnamed facility. She is drugged and is given plastic surgery. While recuperating, she has a flashback showing an unnamed man with a mustache trying to resuscitate her after a breath-holding exercise. He is calling her Sook-hee.
The facility turns out to be part of South Korea's intelligence agency and is run by a woman named Kwon-sook. Kwon-sook tells Sook-hee that to give her a new start the agency has faked her death. Kwon-sook tells her they have given her a new identity and name, Chae Yeon-soo. Yeon-soo says she doesn't care and wants to die. Kwon-sook tells Yeon-soo she is pregnant. Kwon-sook offers her a deal: train with her as an agent, work as an agent, and she will have freedom after 10 years of service. Yeon-soo accepts and while in training, gives birth to a daughter, Eun-hye.
Still at the facility, Yeon-soo is having a procedure to remove a tattoo from her shoulder and while this is happening, she has a flashback to the unnamed man with a mustache giving her the shoulder tattoo when she was 20-year-old Sook-hee. Another flashback occurs, and we again see 20-year-old Sook-hee as a highly-skilled and trained assassin trying to kill an unnamed man with yellow teeth. Sook-hee is captured and, while beating her, the unnamed man with yellow teeth tells her he did not kill her father. Eventually, the unnamed man with a mustache arrives, shoots the man with yellow teeth, and frees Sook-hee. The flashback continues, and we see Sook-hee as an 8-year-old being trained to load a pistol by the unnamed man with a mustache. The man tells the young Sook-hee to devote her life as an assassin to him.
Kwon-sook gives Yeon-soo a folder with the info for her first "assignment." When she kills the target, she looks up to see a young girl on the stairs. This triggers a flashback to 7-year-old Sook-hee seeing her father killed. Sook-hee is hiding under a bed and doesn't get a look at the killer's face; she only hears him whistling an eerie tune. When a man comes back into the room, we are shown that this person is Jang-Chun, the unnamed man with yellow teeth. Jang-Chun was a friend of Sook-hee's father. Her father had stolen a diamond. Jang-Chun sells Sook-hee to a prostitution ring. Sook-hee is about to be raped by a prostitution client when the unnamed man with a mustache arrives and rescues her. We learn his name is Lee Joong-sang. And we learn how it came about that Joong-sang trained Sook-hee to be this killing machine and why she is so devoted to him.
Having completed her first assignment, Yeon-soo is released from the facility and will continue to work for the agency from her own apartment that she shares with her daughter Eun-hye. Unknown to Yeon-soo, Kwon-sook has placed a male agent in the apartment beside Yeon-soo's apartment. His name is Jung Hyun-soo, and he is to befriend Yeon-soo and keep tabs on her.
After a few meetings with each other, Yeon-soo asks Hyun-soo out. While noticing Hyun-soo's tie, Yeon-soo is reminded of a tie she gave to Joong-sang. It is revealed in flashbacks that Sook-hee and Joong-sang had gotten married. We learn in a flashback that the marriage was not the same for Joong-sang as it was for Sook-hee. We learn that Sook-hee says that she is willing to let go of her thirst for revenge if she can get married and live a normal life. Joong-sang sees that his trained assassin would no longer be of much use, so he sets up an act. He stages a wedding with her and pays people to attend the wedding and while on their honeymoon, he fakes saving a gang member called Choi Chun-Mo and stages his own death. When Sook-hee hears he is dead, she loses her mind and goes on a killing rampage and takes out the whole gang (who she thinks is behind Joong-sang's death). Joong-sang has eliminated his rivals and Joong-sang expects Sook-hee to be killed because of her rage and the sheer numbers of the gang. But they are no match. This is the opening scene of the movie.
While on a mission together with Min-ju, a classmate from the facility, Yeon-soo is caught stealing a phone, and in the ensuing fight, Min-ju is killed. The info from the phone has documents about Choi Chun-Mo and the agency is worried that since Yeon-soo knew him, she may be a double-agent. Hyun-soo comforts Yeon-soo and this brings them closer together.
Yeon-soo continues to live at the apartment and the agency has figured their next target for her. The agency wants to do an assassination from a wedding catering company, so it decides to arrange a wedding between Hyun-soo and Yeon-soo. In a callback to the earlier story, the agency pays people to attend the wedding, and Yeon-soo in her wedding gown aims a rifle out a window to her target, whom she sees through the rifle scope. The target is Joong-sang. She can't kill him, shocked that he's still alive.
Joong-sang backtracks the location from which the shots come and identifies Yeon-soo as Sook-hee from the wedding photos. He makes contact with Yeon-soo to verify that it is actually her. He tapes a conversation of the agency and sends it to Yeon-soo. The conversation reveals that Hyun-soo is actually an undercover agent. She turns on the agency.
The agency takes Yeon-soo into custody. In the meanwhile, Joong-sang's gang gets to Hyun-soo and Eun-hye. Hyun-soo tries to tell Joong-sang (on the phone) that Eun-hye is, in fact, Joong-sang's daughter hoping for all the killing to stop. Joong-sang doesn't care for the little girl and tells Hyun-soo to kill the kid in exchange for his own life. Hyun-soo tries to fight the gang but is knocked unconscious and left with the little girl and a bomb.
Joong-sang stages a "rescue" of Yeon-soo from the agency's custody. As she reaches her apartment, she watches as the bomb goes off and Hyun-soo and her daughter both die. She thinks it's the work of the agency. She goes to confront Kwon-sook, but Kwon-sook has news for her: Hyun-soo had found Jang-Chun, the unnamed man with yellow teeth, and got to know everything. This interview was recorded on surveillance tape. Kwon-sook plays the tape for Yeon-soo.
Yeon-soo is consumed with revenge. Yeon-soo tracks down Joong-sang and his gang to a parking garage. She kills all the gang members in the garage and confronts Joong-sang, who escapes to the street and meets his remaining gang members; they all speed off in a shuttle bus. Yeon-soo chases after them. She catches up to the bus, boards it, crashes the bus, and finally holds an ax over Joong-sang's head. He puts his head down and starts whistling the same eerie tune. She strikes Joong-sang in the head with the ax before walking out of the wreckage with the police surrounding her; she smiles a grim smile.