V Shanthi Devi, owner and CEO of Devi Industries in Madras is announced as the number one young industrialist in India. She is a rich and arrogant woman who rules her company with an iron fist. She lives with her father Viswanathan, whom she replaced five years ago as the CEO, and her maid Kannamma, as she had lost her mother 20 years ago. Krishnan, a kind-hearted mechanic working in Bombay, comes home to Madras to see his mother.

Krishnan and Shanthi Devi meet at the airport and their first meeting ends on a bitter note. Krishnan learns that his mother is suffering from paralysis. Krishnan quits his job in Bombay and decides to stay in Madras to take care of his ailing mother. His family doctor recommends Krishnan to meet a renowned businessman for his job. Krishnan goes to meet the businessman and on the way, Viswanathan is beaten by thugs. Krishnan helps him and takes him to a hospital and discovers that Viswanathan is the businessman whom he was going to meet. Krishnan is asked to go to the factory only to discover that it belongs to Shanthi Devi. She refuses to hire Krishnan, but later due to her father's compulsion she recruits Krishnan as Senior mechanic.

Krishnan befriends Meena, Shanthi Devi's secretary. Meena, unlike her boss, is sweet and warm, and instantly falls in love with Krishnan. Once Krishnan saves Shanthi Devi from a falling structure by lifting her, but she slaps him. He returns to her room and slaps her in private. She then realises the incident and promotes him as Section chief mechanic. In the meantime Krishnan is elected as the union leader, defeating the office staff candidate supported by Shanthi Devi. Shanthi Devi is not very happy about him as they have different views and ideas. They have frequent clashes due to this.

Meena decides to marry Krishnan and reveals it to him. Krishnan likes Meena but advises Meena to discuss it with his mother first. Shanthi Devi, on the hand, decides to marry Krishnan, to take revenge on him. She somehow convinces Krishnan's mother to get her married and Krishnan obliges his mother. Krishnan's mother is not aware of Shanthi Devi's plan. Shanthi Devi expects Krishnan to stay at home post marriage but her plan backfires as Krishnan continues as the union leader even after marriage.

Shanthi Devi changes a policy in her company which agitates all the workers and they go on an indefinite hunger strike, which is headed by Krishnan. Viswanathan realises that his company's image is at stake and takes over as the chairman. Shanthi Devi is angered by this move and begins destroying her house, humiliated at having lost to Krishnan. Krishnan's mother learns of their bitter relationship and, despite recovering from paralysis, immediately dies of guilt. An assassination attempt is made on Shanthi Devi by her business rival Sathish, but Krishnan kills him and saves her and ultimately she realises her mistake. Meena is later appointed as the new CEO of Devi Industries and Shanthi Devi remains a housewife to Krishnan.