Guna (Kamal Haasan) is a mentally affected person and receives treatment in a mental hospital in Hyderabad. He does not like his father, and his mother Manonmani (S. Varalakshmi) is a moll in the house that they live. He assumes a fictitious character named Abirami (also the name of an Indian goddess) and registers in his mind that she is an angel who is going to marry him on a “full moon day”. After coming out of the asylum, he believes the story to be true and believes that his Abirami is somewhere around.
A bunch of hooligans led by Guna’s uncle (Janagaraj) trick Guna into robbing a temple of Abirami, an Indian goddess. He happens to see a rich girl (Roshini) in there, right after his uncle tells him that “Abirami will come”. He decides that she is the one, and in the confusion following the robbery, he takes her with him to a lonely, damaged house situated at the top of a hill in Kodaikanal. Police start investigation regarding the robbery and missing of Roshini. Initially, Roshini hates him for his weird nature and for holding her captive.

Prabhu hails from a poor family, and lies to Sukanya about him being poor and marries her. Sukanya’s mother plots to destroy their marriage, but succumbs to their love.

Krishnaswamy (Kamal Haasan) is a widower living happily along with his mother-in-law Saraswathi (S. N. Lakshmi), daughter Kaveri (Mahanadi Shobana) and son Bharani (Mahanadhi Dinesh) in a village near Trichy. Dhanush (Cochin Haneefa), a con from the city, has an eye on Krishna’s prosperity and asks him to join his chit fund business. At first, Krishna is reluctant; however, when a rich friend from a foreign country visits his house, he too wants to be rich like them. Hence he agrees to Dhanush’s proposal and arrives at the city. However, he is unaware of Dhanush’s tricks and when Dhanush swindles away the chit fund money, the blame is put on Krishna, and he lands up in jail. He finds that even his future father-in-law Panjapakesan (Poornam Viswanathan) is also in jail for the same reason, whose daughter is Yamuna (Sukanya), working as a nurse. He advises Krishna not to be angry if the jailor is cruel, as he might be released sooner if he is submissive in the jail. During Krishna’s tenure in jail, Yamuna takes care of his family. Due to unavoidable situations, his mother-in-law dies and his children go missing. Krishna learns this after coming out from jail suffering unnecessary hardships.