Biology teacher Devki is vivacious and popular among her students. At home, however, despite her persistent and warm approach, her stepdaughter Arya remains frosty and distant. Arya is invited to a Valentine-Day party at a farm house; Devki permits this with great hesitation. Arya goes to this party and rebuffs Mohit and his hotshot buddy Charles. Incensed by this very public snub Charles and Mohit and Jagan and the watchman Babu attack Arya when she leaves the party. They violently rape Arya and dump her in a drain. Devki is shattered. Her husband Anand cuts his business trip short and hurries home. Arya recovers and releases a statement naming her attackers.
The case is fast-tracked. Inspector Matthew quickly rounds up the attackers. But the case falls apart. Arya was found to be drinking. The body samples were recovered very late and were too weak to match the attackers. Others at the party provide a strong alibi. The judge acquits. Her lawyer suggests appealing to a higher court but Devki has lost the faith and strength to carry on. Arya, still in shock, tears away from Devki. In deep sorrow Devki realizes that she has probably lost Arya forever.
She recalls the somewhat shady detective DK she had met on the night Arya was raped. A father of a daughter himself, he understands her pain and agrees to help her. She wants information. She wants to avenge Arya.
The watchman is first. Devki seeks the help of her former students, transgenders who deeply understand her plight. They seduce the watchman and drug him. He awakes four days later, still drunk, and finds, to his horror, that he has been castrated and remembers nothing! The hotshot Charles is next. Devki breaks into his home and mixes crushed apple seeds â€“ a source of cyanide â€“ into his fitness powder. Charles is paralyzed. When Mohit visits Charles at the hospital Devki, tipped off by DK, plants apple seeds and other evidence at Mohitâ€™s home and sets off the alarm. Inspector Matthew quickly arrests Mohit; Charles will die soon and Mohit will be the murderer. Matthew finds Devkiâ€™s glasses in Mohitâ€™s apartment and now suspects Devki.
Matthew confronts Devki and sweats DK but there is no evidence. He warns Devki that the fourth man, Jagan, is a hard criminal: tracking him is not easy and is dangerous for her family. Jagan visits Charles and learns that it is Devki who is retaliating. He goes after DK and discovers that Devki is on a holiday at a snow cottage. Jagan kills DK and goes after Devki. Matthew discovers a hidden camera in DKâ€™s sunglasses and hurries to save Devki.
Jagan cuts power at the cottage and shoots Anand. Devki had not expected this and is horrified to see Jagan about to attack Arya. There is a scuffle. Arya runs out into the snow. Jagan pursues her and Devki tries to save her. There are more scuffles and Jagan is about to kill Devki when Matthew intercepts them and tackles Jagan. There is a standoff: Devki points a gun at Jagan and Matthew attempts to talk her down. Arya, in the bushes, overhears Jagan when he angrily relates how Devki finished off the other attackers. Devki will not hear Matthew: if Jagan is left alive he will come after her again and at this point Matthew hands her his gun and urges her to kill him. Devki hesitates but when an overwhelmed Arya acknowledges Devki as â€˜Momâ€™, Devki shoots Jagan dead.