When Jang Ok-ju arrives at Choi Min-hee’s apartment, she discovers her friend dead in the bathtub after taking her own life. Min-hee leaves a final note inside her red ballet shoes box reading: "Please get revenge for me. Somehow I feel like you're the only one who can do it," along with Choi Pro’s social media handle.
Ok-ju uses her surveillance skills to track Choi Pro to his home and plants listening devices. Breaking into his locked drawer, she discovers a collection of USB drives containing non-consensual recordings of women, labeled with nicknames. She locates the drive labeled "Ballerina" and watches footage showing Choi Pro drugging, assaulting, and blackmailing Min-hee, driving her to suicide.
Ok-ju confronts Choi Pro at an underground club named Heaven. Pretending to be a client, she lures him to a private motel room. A violent fight ensues; Ok-ju slashes Choi's face and steals his sports car, but Choi manages to escape. Realizing he is dealing with a lethal threat, Choi contacts his syndicate boss, Boss Cho, and his gang to launch a manhunt for Ok-ju.
Ok-ju visits two veteran gun suppliers in the countryside to purchase an arsenal, including automatic rifles, handguns, and a military-grade flamethrower. She tracks Choi Pro and Boss Cho to their headquarters. In a pivotal subversion of classic action tropes, when Boss Cho attempts to deliver an intimidating monologue, Ok-ju immediately shoots him dead in the head without hesitation.
She guns down the remaining henchmen and pursues Choi Pro to a secluded beach where he tries to flee. After overpowering him in hand-to-hand combat, Ok-ju drags the disfigured predator across the sand, straps him down, and incinerates him alive using the flamethrower. Ok-ju recovers the entire archive of USB drives and a black notebook containing the identities of other syndicate members, ensuring the complete dismantling of the trafficking ring and liberating all surviving victims.