In 17th-century Malabar, Thevan, Arjun Ashokan and Koran, Manikanda Achari arrive at an unfamiliar, forested area and set up camp for the night. During the darkness, Koran is seduced and killed by a yakshi, Amalda Liz. Thevan bolts into the shadows and wanders until he discovers a ramshackle mana in the morning. While trying to crack open a coconut to stave off hunger, he is found by the house’s cook and brought before the lord of the mana, Mammootty Kodumon Potti, who asks about his whereabouts and, upon learning he is a paanan (folk singer), urges him to sing.
Thevan sings, and the lord of the mana praises the song, insisting that he stay for life, even as Thevan longs to leave. The cook, showing Thevan to his room, warns him not to ask questions about the house or venture into off-limits areas. In the days that follow, Thevan learns from the cook that Kodumon Potti is a descendant of the sorcerer Chudala Potti, who was gifted a mystical goblin helper, a chathan, by the goddess Varahi. The chathan’s torment drove it to kill Chudala Potti and his family. Pretending to be strong and in control, Kodumon Potti eventually defeated the Chathan and chained it in the mansion’s attic. Thevan senses the cook’s resentment toward Kodumon and begins to suspect there is more to the house than meets the eye. The cook, in turn, warns him not to trust the master, and Thevan learns that a singer who stayed there before him vanished, buried in the backyard as his mind fracted.
One day, Thevan spies the cook digging a grave in the yard, probably for himself. Terrified, he tries to leave, but a spell keeps him from crossing the gateway, and Thevan pleads with Kodumon, who refuses to let him go. He also realizes his memory is slipping, fading from his own name and origin. The cook reveals that the grave is not for Thevan but for the real Potti, whose corpse lies upstairs and is later buried. Thevan concludes that the Potti downstairs is the chathan in disguise, imprisoning the true Potti and driving him insane, which led to his death. The only escape is to defeat the chathan by extinguishing an ever-burning lamp in a secret granary chamber and trapping the creature in a special chest.
In a confrontation with the impersonator Potti, the cook steals the key to the hidden chamber and blows out the lamp, weakening the chathan. Thevan and the cook fight the reptilian intruder as flames threaten to consume the mana. The cook, revealed to be Potti’s illicit son, seizes the ring and tries to don it to assert his rightful claim over the chathan, but Thevan intervenes, fearing the ring’s power will corrupt any bearer. The two clash as fire tears through the mana and the mansion begins to collapse around them.
Thevan is later seen walking away from the wreckage of the mana, but the cook attacks him in the confusion. The cook then discovers that he is not the real Thevan but the chathan inhabiting the body. The real Thevan is shown to have perished in the mana’s collapse. Terrified, the cook flees into the forest and meets an imperial Portuguese soldier crossing the river; an attempted strike fails, and he falls to gunfire. A platoon of Portuguese soldiers emerges from the forest, crosses the river, and advances toward the mana’s ruins, while the chathan inside Thevan’s body slithers away, still wearing the ring.
