A love affair between Thamarai Nachiyar (Khushbu) and her maternal cousin Nellian Kodan (Jayaram) is poorly received by their family, especially since he is not financially well off. Thamarai's father, King Periyamalai Kozhundhu Gounder (Vijayakumar), arranges for her marriage to Mandhiyappan (Prakash Raj), the ruler of a neighbouring country. Thamarai rejects the arranged marriage, angering Mandhiyappan. She later marries her lover, who had come to see her marry Mandhiyappan, and challenges her brother Chinnamalai Kozhundhu (Ponvannan) to marry his daughters off to her sons (the marriage of cousins is a gounder custom). Periyamalai Kozhundhu disowns his daughter for choosing Nellaiyankondan and banishes them from his kingdom.

Many years later, Mayavar (Nassar), a chieftain of a village in Periyamalai Kozhundhu's kingdom, encounters twin brothers Ponnar and Shankar (both played by Prashanth), who are being tutored in martial arts by Rakki Annan (Rajkiran). Ponnar and Shankar are valorous and compassionate to the sufferings of the poor. One day, the twins save two sisters, Muthaayi (Pooja Chopra) and Pavalaayi (Divya Parameshwaran), from death. The girls are later revealed to be daughters of Chinnamalai Kozhundhu. Impressed with Ponnar and Shankar's valour, Chinnamalai Kozhundhu agrees to marry his daughters off to them.

A flashback reveals that Ponnar and Sankar are actually Thamarai's sons and that Rakki, who was then a servant of Nellian Kondan, had saved the twins as small children from Mandhiyappan. Mandhiyappan had attempted to avenge himself on Thamarai for rejecting his hand in marriage. He learns that the twins are still alive and hatches a conspiracy to kill them. He tricks Kali Mannan (Napoleon) and Periyamalai Kozhundhu into helping him. This leads to an intense battle which ends with good prevailing over evil.