A young girl is followed by a "curse" that is killing off many of her family and friends in the most brutal ways imaginable. Will she be able to discover the secret behind this murderous mystery before she too becomes it's victim?
The movie begins with a child witnessing a woman's mysterious murder with her blood smearing over the television set. The child begins to slowly inch closer to the dead lady, and as he reaches out to touch the knife, her eyes open and she utters a hair-raising scream. At the opening credits newspaper articles about inexplicable murders taking place and the movie title appears on the screen.
Ga-In (Yoon Jin-seo) is a full-time student in Korea with a talent for fencing. However while in school she is puzzled by a strange male student who Ga-In catches watching her. Ga-In and her family come to her aunt's, Jee-Sun, wedding. Before the wedding, Jee-Sun is pushed off of the third story balcony, and is immediately rushed to the hospital. After the rest of the family leaves the hospital, Ga-In stays behind and waits with her boyfriend, Hyun-Joong, while her aunt recovers. As they pass Jee-Sun's room, they witness Jee-Sun's younger sister, Kim Jung-Sun, repeatedly stabbing her.
Kim Jung-Sun is arrested for the murder of Jee-Sun, and is held for questioning. It is soon revealed that the family believes that their family is cursed and at least one family member dies in incomprehensible ways. In this case, a hidden force possessed Jung-Sun and caused her to kill Jee-Sun. After the incident, Ga-In begins to have forewarnings, while dreaming, about a woman who was covered in blood who tells her she is next. The next day at school, Ga-In is resting in the nurse's office while another student visits her class room looking for her. He wants her to be in a PR video they are making, and explains it is important that she is the one in the video. The teacher suggests Eun-Kyung, the top student, instead, but the young man refuses. Ga-In sees a vision of a shadowy figure who frightens her with a misshapen hand. Later, Eun-Kyung visits Ga-In at the nurse's and attempts to kill her with a pair of scissors. During the struggle, Eun-Kyung is stabbed instead, and it is later revealed that she has transferred to a different school. Later that same day, while she opens the locker a deformed figure tries to grab her, Ga-In is confronted by her teacher, who then blames her for Eun-Kyung leaving and tries to kill her. Luckily, Ga-In is saved by a classmate.
After a series of perilous incidents, Hong Suk-Min, an eccentric student who is rumored to have killed his own father, knows the truth about the family curse. He advises Ga-In to trust no one, including herself. After talking to Hong, she visits Kim Jung-Sun to ask her about the murder. She tells her that Jee-Sun's husband is Jung-Sun's ex-boyfriend, and she had required revenge on Jee-Sun. She tells Ga-In that an unknown force possessed her and coerced her to kill her sister.
That evening, after a mysterious wind closed the gate after she received the invitation, the classmate that had saved her from the teacher has come to have his try at eliminating her by using a baseball bat. She gets away and runs inside only to find her mother throwing knives at her. Frightened, she then tells her father that she no longer feels safe inside her own home with her family, and is going to get away for a little while. Her father then tells her that there is a forgotten family member in a different village, named Hwang Dae-Yong. On the bus, Ga-In meets Hong again, and together they visit Dae-Yong.
While at his home, Dae-Yong tells them that in order to not be affected by the curse that surrounds the family, Ga-In must not meet someone like herself. Dae-Yong begins telling them the story of when he learned of his wife's alleged affair. While waiting to cross the street, Dae-Yong was suddenly overwhelmed with jealousy and pushes his wife into the path of an oncoming bus. Upon being released from prison, Dae-Yong tries to find the unknown force that controls him. When Ga-in discovers a secret closet that contains past newspaper reports about savage deaths which were taking place, then while she's sleeping a deformed being try to haunt her.
After Ga-In and Hong Suk-Min return home, Dae-Yong commits suicide in order to stay away from the curse. Later at school, Ga-In has an apparition of her best friend pushing her from a balcony, and glares at her with a sinister face. Ga-In realizes that she really can not trust anyone and leaves school. One night she mystifyingly wakes up in her bed and makes her way downstairs. However, recalling Suk-Min's warning, she turns around and sees her parents mysteriously killed. It is divulged that Hyun-Joong is the one who eliminates her parents, and that he had manipulated Ga-In to get close to her family to demand vengeance on Ga-In's father. Ga-In tries to fight off Hyun Joong, he stabs her for a short time as she tries to save her younger sister, and is making a scheme to set the house on fire and it will be turned into hell. Ga-In suddenly awakes and impales him. Just as he is about to strangle her, both sisters quickly regain consciousness, and finally defeats and stab him and leave him dead as the house begins to burn in a mass of flames.
In the hospital, after the fire happened last night, Ga-In and Ga-Yun are placed in the same room. Ga-In is having nightmares of her aunt killed her comatose sister all the people who planned to eliminate her, and is woken by her sister Ga-Yun. Ga-In has a hallucination of Ga-Yun taking a knife from her pocket, and they both struggle and the knife ends up stabbing Ga-yun. Ga-Yun cries and asks Ga-In how she could do this to her own sister. Hong Suk-Min is then seen on the couch and exposes his true individuality, the curse. Only he can be seen by Ga-In and the people he controls. Ga-In looks down at Ga-Yun and realizes that it wasn't a knife in her pocket, but instead a burnt family photo. Hong Suk-Min then tries to eliminate Ga-In. Ga-In stabs Hong Suk-Min, but in reality she stabs herself because he is controlling her from the inside.
In the epilogue, a boy is being verbally assaulted by his teacher. After the teacher leaves, Hong Suk-Min appears in a new body and asks the boy if he wants help to get back at the teacher.
Credits to Wikipedia.