During the 19th century (1881) in a village in Bengal Presidency, a 5 year old Bulbbul (Tripti Dimri) is married off to Indranil (Rahul Bose), a wealthy lord, when she is barely five years old. Bulbbul is scared and lonely to be sent to a strange new home at such a tender age. She is close with Satya (Avinash Tiwary), Indranil's youngest brother, who is closer to her age. Bulbbul and Satya grow up together, telling each other stories of a witch ("Chudail"). The Chudail had twisted feet, was blood thirsty and was patient for her prey. It is indicated that Indranil's mentally challenged twin brother Mahendra had his eyes on Bulbbul from the day she stepped into the house, and he saw her as a doll. Binodini is Mahendra's wife.Twenty years later, Satya returns home from London. The village lives under the wrath of a Chudail and several deaths have been attributed to it. In the interim, Indranil's twin brother Mahendra (Rahul Bose) was killed in what was believed to be a Chudail's attack. His widow Binodini (Paoli Dam) now lives in an outhouse. Indranil has left the village and Bulbbul has taken over his responsibilities at the mansion. Binodini claims that Mahendra was killed by the Chudail on the day of the Kali prayers. Satya says that maybe Mahendra was killed by a man-eating tiger. Binodini is adamant that she saw backward, blood-soaked feet marks on the floor.The village doctor, Sudip (Parambrata Chattopadhyay), regularly visits to check Bulbbul's feet due to an incident she refuses to discuss. Satya takes it upon himself to solve the mystery of the Chudail and even organizes daily night patrols to hunt for the killer. When another man is killed, Satya suspects Sudip as Sudip was on patrol on the night of the incident and had separated from the main group when he wandered off, seemingly following the Chudail.In flashbacks, it is revealed that Binodini had been jealous of Indranil and Bulbbul. Binodini felt that she was the one who took care of Indranil, and yet he had eyes only for Bulbbul. She took exception to the fact that Satya and Bulbbul were still very close, even though they were grown ups now. Binodini had hinted to Indranil that Bulbbul had feelings for Satya. With his mind poisoned, Indranil sent Satya to London to study law to separate the two. Bulbbul is distraught at losing Satya, whom she considered her dearest friend. Indranil mistakes Bulbbul's pain at losing her best friend, as her illicit love for Satya. Indicative of his double standards, Indranil was having his own affair with Binodini. Bulbbul and Satya had been working on a story together; heartbroken, she burned the manuscript in the fireplace. Influenced by Binodini, Indranil retrieved the burned pages; upon reading them, he became convinced of Bulbbul's feelings for Satya. Enraged, he beat her and mutilated her feet with iron bars. Dr Sudip is called to attend to her and is told that Bulbbul fell from the stairs. Indranil decided to leave home after this incident but promised to keep sending money to support the estate. While she is bedridden, Mahendra sexually assaults her, accidentally suffocating her while caught up in his sadism. Binodini knew what Mahendra had done, and yet told Bulbbul to keep quite about it. Binodini cleaned up Bulbbul before anybody else saw her.Following this, there is a supernatural change in Bulbbul - she returns with a mission to help the women in her village fight back against injustice. She goes through a symbolic transformation each time, represented by a blood-red moon which indicates that the goddess Kali is supporting her. She punishes men who abuse, murder, or take advantage of girls by killing them; she is in fact the Chudail the villagers attribute the killings to, distinguished by backward feet. Bulbbul also killed Mahendra.In the present day, Satya continues to doubt Dr Sudip as he is near every incident of murder or suspicious death in the village. Satya is also not happy that Sudip and Bulbbul have feelings for each other. Satya confronts Bulbbul and says that perhaps Indranil left her as she had feelings for Dr. Sudip. He says that it would be best if Bulbbul went back to her family in case Indranil did not accept her. Meanwhile, Bulbbul is informed by a village boy that his mother has committed suicide after her husband chose his second wife over her; Bulbbul seeks out the man.Satya is escorting Sudip to Calcutta. The driver of the carriage (the village boy's father Bulbbul had been seeking) is killed by the Chudail, making Satya realize that Sudip is innocent. Satya shoots the Chudail and Sudip realizes Bulbbul is the Chudail. During a brawl with Sudip, Satya accidentally sets the forest on fire and also discovers that Bulbbul is the Chudail. Upon realizing this, he cries in agony, while Bulbbul takes refuge on a tree and is slowly engulfed by the flames.A year later, Indranil returns to his empty estate. Satya has departed, guilt-ridden for what happened with Bulbbul and feeling like he too was becoming like his brothers. That night, Indranil is awoken by Bulbbul, who smirks at him, hinting that she will kill him as revenge.