The basic idea of "Deepavali" is that Billu is the foster child of the community, but he is the son of Mudaliar. Mudaliar is well respected in the community. Billu falls for Susi, and he ends up meeting her at the railroad station. Susi is at the railway station because she has traveled from Bangalore to Chennai. She will be staying at Sait's place, and she use to work for Susi's dad named Chidambaram. He is a thug in the community, but he eventually decided to fly right. Susi really wants to be loved, and so she will do anything for love.
The community Godman decides that she is right for Billu, but she does not agree. Susi does not like her father because she is scared of him. Susi does not want her life to be turned upside down if they decide to fall in love with each other. She soon discovers that she cannot stop her negative feelings about the situation, and so she starts to get along with Billu. She does not expect what happens next. Susi is acting abnormally when she meets her pal at a resturant as she denies knowing her friend. Her pal, Revathi, walks away from the situation confused as what is going on. No body seems to know what is going on.
This situation causes Susi to become extremely emotion, and so she ends up leaving the restaurant in a fast paced manner. Susi comes clean with Billu; she is suffering from post traumatic event disorder. Susi does not remember what happened during the accident, and so Billu takes her to the doctor. They are happy to learn that her situation is treatable, but you will have to watch the film to see how it ends!
The cast of the film and their respective parts are: Jayam Ravi as Billu, Bhavana as Susi, Raghuvaran as a Doctor, Vijayakumar as Mudaliar,Cochin Haneefa as Settu, Lal as Chidambaram, Soori.