Three girl students are found to have committed suicide in a boarding school in Alwaye under mysterious circumstances. Their boyfriends are interrogated by the cops, and one of them, Ananthu goes into depression. He is the boyfriend of one of the dead girls, Gowri. The case remains unresolved.
A year later, investigating officer Sreekanth's niece Parvati joins the school, and is given the same room where Gowri used to stay. Soon Parvati starts acting weird, which is noted by her classmates, and even the school driver and peon start to also see Gowri appearing at night in the school corridors. Gowri's spirit soon appears before Parvati, seeking her help. At times, it also enters Parvati, making her act as if possessed. It once made Parvati go to Ananthu's house to cheer him up. Gowri and her two friends were very happy go lucky characters in the school, and something happened during a picnic which changes their lives forever.
The film then moves to Aloyshi, the school music and dance teacher, and a lecturer Jennifer, who seem to be very friendly. Aloyshi takes a liking for Parvati, and encourages her to give splendid performances at all college functions, which she does with the help of Gowri's spirit. Soon afterwards, Gowri's spirit, in the guise of Parvati, goes to Jennifer's house and immolates the whole place, killing her. Sreekanth sees a laptop at Jennifer's house and gets it repaired. Later, he finds Jennifer's laptop loaded with nude pictures of the girls staying in the hotel. He orders investigation into the matter. Sreekanth also comes to know that Jennifer was an immoral woman. He visits Aloyshi and notes that the latter is a very shady character.
Fed up with Parvati's maniacal episodes due to possession, Sreekanth calls doctors but they are not able to help much. Finally he calls a Tantrik who casts Parvati/Gowri under a spell and makes her tell all that is going on. It is then revealed that the music teacher is a womanizer and he actually tried to rape Gowri at the picnic. It is also shown that he has taken nude pictures of the girls, and threatened to reveal them to everyone if they did not give in to his desires. Jennifer had been hand in glove with Aloyshi. The panic stricken girls then committed suicide in the school, but as Gowri did not die immediately, Aloyshi and Jennifer arrived early at the scene in the school and gave her more poison to hasten her death. Thus, Gowri returned for revenge, through Parvati.
Aloyshi is now arrested by cops but he manages to get bail. Gowri's father attacks him on the way but Aloyshi throws him into the river and escapes. Gowri /Parvati goes to Aloyshi's house one night and throws him from the terrace, thus killing him. Sreekanth arrives too late, and returns home to find that Parvati had never gone out of the house that night!
With her revenge now complete, Tantrik orders Gowri to leave, but she says that she wants to take her beloved Ananthu with her, and goes as Parvati to kill him and take his spirit away. Sreekanth runs to the hill where Parvati is about to jump off the hill with a reluctant Ananthu, and manages to put a protective bangle on this hand,thus dis-powering Parvati. Parvati is then taken to the tantrik, and he drives Gowri's spirit out of her. The spirit bids goodbye to Parvati,and she returns to normal.
The film ends with Parvati joining school again with the old classmates.