It seems very much pleasurable that young directors could be explores the villages often, where one can find the real heart beat of the humanity. Thirumagan is another film with sensational story with the flavour of the soil after Paruthi Veeran. Rathna Kumar, the writer of Kizhakku Seemaiyile and Karuthamma has made his debut sensibly and completely changed the playboy image of S.J.Suryah. The story starts in a remote 'karisal kaadu' near Theni. Thangapandi (Suryah) is the only son of Malaisamy (Vijayakumar), who had once enjoyed huge wealth and power in that village. He is the man of honest and humanity, which earns the admiration of the Villagers.
Thangapandi, a carefree youth, falls in love with Mayyakka (Meera Jasmine), a poor woman, who earns her livelihood by selling pots. But his mother and sister had plans to marry Raasaathi (Preethi Varma) a close relative (Murai Penn) of Thangapandi. Meanwhile, Maina (Malavika), a local sexy folk girl also runs around romancing him. But Thangapandi gets acquainted with Mayakka and decided to marry her. Without the knowledge of this, Malaisamy gave word to his friend Sivalingam (Radha Ravi), that he would arrange for the marriage of later's physically handicapped daughter Vairam (Lakshana) with his son Thangapandi. He gave that promise on the basis of his strong belief on Thangapandi. Malaisamy told that his son is like a Raman in keeping his father's words. But things are completely gone against his wishes.
Thangapandi's mother and sister compelled him to give away his love with Mayakka and marry Preethi Varma. His father Malaisamed wished him to marry Vairam. But Thangapandi convinced his father Malaisamy and got his blessings too for his love. But on the very next morning people find his dead body in the temple. He had left the world with the worries of not keeping his words to his friend Sivalingam. Later only Thangapandi came to know about his father's belief on him. Immeadiately Thangapandi took a sensational decision on his marriage with the help of Mayakka. That gives a new dimention to the film also.