Pazhani (Sivaji Ganesan), a widowed farmer, lives with his three younger brothers, Velu, Raju (S.S. Rajendran), and Muthu (R. Muthuraman), and orphaned niece Kaveri (Devika). The entire family toils on land leased from Chokkalingam (TS. Balaiah) and lead a content life together. Velu's wicked wife, Nagamma leaves him after a fight with the brothers. After much pacification by Pazhani, she returns to live in a nuclear family with her husband. Muthu likes Emily (Pushpalatha), a college student.
Chokkalingam is a cunning and wicked person who is encouraged by his accountants Kalyanam (M.R. Radha) and Santhanam (Nagesh). Chokkalingam, who has an eye on Emily invites her home and tries to molest her, and Muthu, who happens to be there, rescues her, after beating Chokkalingam. Chokkalingam decides to take revenge on Pazhani's family. Pazhani and his brothers find a treasure and since its Chokkalingam's land, they hand it over to him. The Police enquires Chokkalingam and he shows a smaller pot of treasure. However, when Pazhani is interrogated, he honestly states that it was a bigger pot of treasure, leading to a raid and seizure of the treasure in Chokkalingam's house.
Chokkalingam, in anger, sells the leased land and Pazhani pleads for mercy. But Chokkalingam pays no heed. Meanwhile, Emily completes her studies and leaves for Chennai and this saddens Muthu.
Vinoba Bhave's Bhoodan (land donation) Movement gains momentum in all villages and Chokkalingam generously donates 5 acres of rocky and barren land. The same land is donated by the organizers to a deserving Pazhani. Pazhani motivates his frustrated brothers to work and make the rocky and arid land fertile. Chokkalingam cunningly offers Rs.2,000/- to Pazhani as a loan after obtaining his signature on a blank stamp paper for developing the land.
A jealous Nagamma spreads a rumour that Chokkalingam favours the family because he is in a relationship with Kaveri. Pazhani immediately announces the engagement of Kaveri and Raju. Furious Nagamma poisons Pazhani's cow and Velu suspects Nagamma and while scolding her, he is bitten by a snake and dies. Nagamma reforms, shocked with the sudden demise of her husband. As per Velu's desire, the marriage of Raju and Kaveri takes place.
It is harvest time and Chokkalingam sends his people to harvest at the land developed by Pazhani with his brothers. Pazhani and his brothers get shocked and demand the reason. Chokkalingam shows the borrowing of Rs. 12,000/- on the stamp paper signed by Pazhani and states that since he did not repay the loan, he is harvesting to recover the dues. Pazhani is shocked at Chokkalingam's lies and deceit. Raju and Muthu get demoralized and leave the village. Kaveri decides to stay with Pazhani, who is devastated after losing his land and brothers.
Raju and Muthu meet Emily at Chennai and with her help get a job and save money to buy land for their brother. Time passes and Raju and Muthu manage to save and convey this through a letter to Pazhani. But Gopal, a co-worker steals that money. An angry Raju attacks Gopal and is jailed for assault. Emily's mother dies and Muthu marries Emily. Pazhani, on receiving the letter comes to meet his brothers and gets shocked to know that Raju is jailed and Muthu is married. Dejected with life, he returns to the village.
Meanwhile, Chokkalingam tries to molest Nagamma and she escapes. To take revenge, Chokkalingam brands her a prostitute and brands Kaveri who comes to her support and they are excommunicated from the village. Pazhani hears this, gets angry with the villagers, and becomes insane. Raju, upon release, returns to the village to see this and goes to attack Chokkalingam. At the same time, the villagers who have been cheated by Chokkalingam join hands to attack him. A scared Chokkalingam takes refuge in a temple. Pazhani intervenes and saves him and asks everyone to forgive him. Pazhani's forgiving attitude reforms Chokkalingam and he apologizes for his crimes and surrenders to the Police. Meanwhile, Santhanam finds out that most of Chokkalingam's lands did not belong to him. The lands are taken over by the cooperative society and distributed among the landless villagers, including Pazhani's family. Muthu also returns to the village and everyone unites to work and reap the benefits.
[from the book Pride of Tamil Cinema: 1931 to 2013 by G Dhananjayan, Blue Ocean Publihsers, 2014]