Plot
Muthaiya and Velaayi are lovers. However, Muthaiya marries the daughter of a rich, but an equally sick man; since, the rich man's daughter rejected him during the wedding day. Muthaiya eyes a second wife, transferring the wealth, to Chennai, for treating his father-in law. The rich man dies, after one year. Muthiah's wife gave birth to a girl, named Rani. Muthiah harasses his wife consistently, due to the wealth inherited, by his wife. Velaayi, manages to know Muthaiya's address in Chennai, from his uncle. Providing a letter to Muthaiya, which invited his wife. Muthaiya plans a plot with intentions to murder, his wife; excusing himself to a visit in the temple, instead delivering a letter to Velaayi.
While travelling towards the temple via a boat, the boat is capsized with the help of Velaayi, as a part of Muthiah's plan. Muthiah manages to save himself and his daughter. He secretly sends money to look after his daughter, marrying Velaayi. As years pass by, Muthaiya visits Rani, his daughter, without Velaayi's knowledge. Rani and Sivagami, study in the same college. One day, Thambi a.k.a. Nalla Thambi visits his sister, Sivagami, in her hostel. Both the siblings including Rani, get acquainted. Rani and Sivagami, finish their studies, returning to their respective villages.
Thambi and Sivagami were driven out of their house, since, both of them oppose their father to get married the second time. Rani joins as a secretary, in Muthaiya's office, without revealing to anyone that she is Muthaiya's daughter, of her first wife. While Thambi gets acquainted, to Raman, while looking for a job in the city. Thambi and Sivagami, move to Raman's house; asking for a portion of the rental, since, Thambi can not find a place for living. Raman's father, Balaraman, and Raman's grandfather, Parasuraman, likes Thambi's attitude, agreeing on his rental. Thambi manages to get a job, from Muthaiya's company, due to recommendations from Rani. Sivagami and Thambi, throw out a party to Rani. However, Kannaiyah, Velaayi's brother, and Muthaiya's brother-in-law, arrives there, leading to a dispute with Thambi. Muthaiya learns of this, giving a friendly warning to Thambi and Rani. Meanwhile, Raman falls in love with Sivagami, get married, while getting clerked as an operator, at Muthaiya's office. Rani, too, falls in love, with Thambi. Kannaiyah, alerted by this, pressured Muthaiya to dismiss Thambi. However, Rani's intervention helped Muthiah to accept Thambi. Kannaiyah grudges against Thambi, vengefully waiting for his turn.
Kannaiyah eventually follows Rani, finding out Muthaiya is Rani's real father, thus, revealing to Velaayi. Muthaiya persuades Rani, to marry Kannaiyah, ending up rejected. Muthaiya, then meets Thambi, showing Rani as his own daughter; persuading Thambi, to reject Rani. Thambi reluctantly nods in an agreement to cast certain aspersions, as a drama, to cheat Rani. Rani mistakenly believes this, reaching to Velayi. Muthaiya's health considerably deteriorates, allowing Kannaiyah to lead the office. Thambi and Kannaiyah, hold up a petty dispute, resulting in Thambi's resignation from the office. Velaayi prepares for engagement, between Rani and Kannaiyah. Thambi attends the engagement, visiting Muthaiya; his honesty exposes the plot to Rani. Cancelling the engagement. Velaayi and Kannaiyah, try to blackmail with the letter, which Muthaiya wrote, before the capsize of the boat. However, Muthaiya showed no concerns, preparing to face the consequences. This results in a report, to the enforcement officials about Muthiah's letter. However, after a series of events, it was acknowledged that his first wife, is still alive. Rani's caretaker, read the news that Muthaiya is arrested. Kannaiyah telephones this matter to Velaayi, planning to kill Muthaiya's first wife. Raman (as an operator of the office) spies this, informing Thambi and Rani.
Thambi rushes to save Rani's mother. During the fight, both Velaayi and Kannaiyah are killed. Rani and Thambi, get united once again.
