The film begins with happening in the cornfields in a village in South India, where a British forest ranger, who is in charge of the fields, has been alerted by some strange noises coming from deep inside the fields. He sets out with his dog and searches for the source of this strange noise, then suddenly the dog is being dragged inside and brutally killed by an unknown beast creature. Then, the forest ranger is also dragged inside and killed by the creature. Then the film shifts to the 1970s, where a college farewell party for Sir Arthur Wellington College is taking place. Two college friends, Amudhan and Vendhan, who is the son of the alcoholic college watchman Vethagiri, have decided to stay back in the college hostel and spend the vacation there. This is mainly because Amudhan's college girlfriend Poongavanam, who lives in the nearby village of Poomanandhipuram, where her father is the village landlord, so that he cannot miss her during the vacation. The only thing that lies between the college and the village is the same cornfield, which is now currently being protected by a big wall that is believed to be the hunting grounds of the strange creature, that the people now call Ambuli. Though some people called it a myth, many believed that Ambuli did exist. One night, despite warnings from Vendhan, Amudhan decides to go through the cornfield to reach Poomanandhipuram to meet Poongavanam. He makes the first trip successfully, but while he returns, he hears the same strange noise and is chased and thrown off his cycle by Ambuli, which is not yet shown on screen. Amudhan runs for his life and reaches the college, where he meets Vendhan, tells him what happened, and reveals to him that Ambuli is real. Vendhan is little convinced by Amudhan's narration of his story, and they both decide to visit the cornfield together that night to see what is happening. They both travel the entire field, reach a corner, and find a wooden cabin, which is the place where the British fo