or mentally ill patient. The temple is closed from 6 pm every evening until 6 am the following morning. It is believed that Siddhars enter the temple past its closure for the day, and perform their rituals and prayers and leave before dawn, and anyone who disturbs the prayers of the Siddhars is done away with by the guardian of the temple, Kaalabhairavar, who is believed to guard the temple during the night in the form of a dog. This belief attracts a number of rationalists to the temple, who want to try and solve the mystery. One such rationalist, a journalist names Srikanth (Indra Soundar Rajan), hides in the temple when it is being closed for the day, in an attempt to find out what really happens in the temple in the dark. However, as if the villagers' fear is made true, Srikanth is killed by a dog while he is inside the temple. Hence, the entire village is convinced that the temple of Chitheshwarar is actually a den of heavenly Siddhas who pray during the night, leaving ordinary people to pray during the day. Srikanth's friend, Mani Sundaram (Ramji) is the young son of the temple's chief priest. He is a rationalist, who does not believe in myths and rituals. Instead, he chooses to rationalize his beliefs, and hence often ends up at odds with his father with regard to the temple's mysteries and rituals. One by one, four people are killed inside the temple, including a police inspector who is there to investigate the mystery. At this juncture, Dr. KR (Delhi Ganesh)—once a great psychiatrist, but now intellectually disabled—strays into the village, and is admitted to Oomaisaamy's ashram by Mani. Prasad (Prithviraj), Dr. KR's son, comes in search of him, and ends up being a guest to Mani and his sister Lalitha (Vasuki). As Mani and Prasad try to reveal the temple's mystery even more, they come to know that Dr. KR is actually acting as a retard, and he too is trying to do the same. But Dr. KR has personal intentions. He had been regarded as one of the best psychiatrists of India, and an Indian Central Minister admits his intellectually disabled son to his hospital for treatment. But Dr. KR is unable to cure the Minister's son even after giving his best for the patient. Enraged by this, the Minister ridicules Dr. KR and