The town of Jayshankarapuram, home of Tamil-speaking cowboys, is ruled by a one-eyed tyrant named Kizhakku Kattai (literally translating to East Wood as in Clint Eastwood), who rules over other villages as well, and is always surrounded by his assistants: a cowgirl named Pakki and an outlaw named Ulakkai. In order to free their town from Kattai's rule, Bilagiri James, Dagelandi, Jada, and Viruma travel to a neighboring town, Holaypuram, to seek out a savior.

There, they encounter Singaram, a man with a noble heart who has been sentenced to death for duty negligence. The gang saves Singaram from execution and explains their situation. Singaram learns why he was chosen. The brave Singam was the previous marshal of Jayashankarapuram who bore a striking resemblance to Singaram, and also was the only one who stood up to Kattai's tyranny. Singam disappeared under mysterious circumstances years ago, and the town was left defenseless.

Thus, Singaram is brought to the village and is passed off as Singam. Singaram learns to adapt to his new name, learning all the hero's skills and tricks. He wins the respect of the village seniors, which includes Paandu Paramu and Keluthi Amma. Soon, a girl named Baali falls for Singaram. He later surpasses the original hero's prowess, though initially, it is due to dumb luck. In between the hero's and the villain's camp is a Red Indian village where the tribals are pure vegetarians. With the introduction of this village, Athirikesa, the leader of the tribal group, his father Rangula, and his beautiful daughter Thumbi are also introduced.

The villagers at Jayashankarapuram find a map that is hidden in their "MGR Timesquare", but it is only one half they have. They have to find the other half to hunt for treasure that is preserved and hidden somewhere far away. Unfortunately, Kattai has other plans. He negotiates a deal of freeing prisoners in exchange of the treasure. Singaram and the folks find the treasure in an Indiana Jones-esque adventure. They successfully find the treasure and escape the cave. But, it is revealed that Dagelandy is a right-hand man of Kattai, who was spying Singaram's gang all along. Kattai also reveals that he killed Singam a few years ago and challenges Singaaram to a duel in front of the people. While Kattai gains the upper hand initially, the thought of Singam's death in the hands of Kattai infuriates Singaram and he starts beating up Kattai. Kattai is eventually shot dead by Pakki, out of her love for Singaram and she leaves the place with her cronies. Peace prevails within Jayshankarpuram's inhabitants and the red Indians.

Singaram is hailed as a hero in Jayshankarapuram and is presented with a large diamond and a platter of gold coins of the treasure as a reward by the people. However, Singaram declines the gold coins for the diamond, instead asking the people to use the coins to build a school for the children, while stating that education is important and is to be imparted to all. He is given a heartful farewell by the people and rides off. On the way, Baali stops him saying that while he took the diamond, he was leaving his "life" behind. Singaram smiles and they both ride off in the sunset.