Prasath (Rajinikanth) and Balaji (Kamal Haasan) are roommates in a city. Balaji falls in love with Selvi (Sridevi) who lives in the same apartment complex. Prasath, who has his eyes on Selvi, pretends to back Balaji's love while secretly hoping to create a divide between them. Selvi realizes Prasath's evil intentions when she finds out that he has seduced an innocent girl living in the same apartment complex. However, she is unable to convince Balaji, who hero-worships Prasath.

Things come to a head when Balaji and Selvi go for a picnic by the lake and Balaji decides to invite Prasath along. As the three of them head to the middle of the lake on a boat, Balaji topples over by mistake. Prasath refuses to jump in and save Balaji, on the pretext that he does not know swimming. A devastated Selvi returns home to another shock — her sister (Y. Vijaya), who plays small roles in movies, has been in a fire accident which has left her face permanently scarred. Overnight, Selvi's life undergoes a drastic change.

Prasath becomes kind towards Selvi and she comes to his house and lives as a maid. Prasath lives with his father (Calcutta Viswanathan) and his younger siblings. His father wants Selvi to marry Prasath. In an attempt to salvage her life, Selvi decides to marry Prasath's father in the absence of Prasath. After her marriage to Prasath's father, she decides to use her 'mother' status to exact revenge on Prasath and gives him a shock when he returns.

The movie ends with lines in Tamil, roughly translating to: "When it is time for a seed to sprout, if the conscience cannot empathise; and only after the incident, is the conscience present! When conscience grapples with oneself for selfish ends; in the evildoer's eyes, his madness will be his conscience!"

• Sridevi as Selvi
• Rajinikanth as Prasath
• Kamal Haasan as Balaji
• N. Viswanathan
• Y. Vijaya
• Rajamani
• Anupama
• Baby Indira
• Kalavathi

The music for the film is scored by M. S. Viswanathan and lyrics by Kannadasan.