Jambhavan movie is about Velan (Prashanth) who is a responsible son of a village landlord (Vijayakumar). Adored by the villagers for his good deeds, Prashanth gets a shock when Vijayakumar informs that he is his foster son.A shocked Velan sets out on a mission to know about his past. He reaches Chennai and comes to know that his family members were killed by a dreaded gangster Deva (Vijayan). He had then vowed to kill him and his gang. In the name of Jambhavan, he starts to kill rowdies in the society.Suffering an injury in his head, Velan loses memory and is later adopted by Vijayakumar. He comes to know that his job was just half-done. The rest is how he puts an end to Fefsi Vijayan and his men coming to Chennai.

Leelatharan aka Lee (Sibiraj) hangs out with a bunch of merry youths who do practically any work and play football in other times. It is a strong-willed and thick-tied group. Chellama (Nila), a worker in a facility for the mentally-challenged, is also kind of a groupie. Life is all merry and mirth till she espies Lee & co, attempting an assassination of sorts on a minister. The bid fails, but Chellama is shocked and so are we. Why would this bunch want to take a crack at the murky world of politics and cricket?

The movie begins at Pachai Theevu, ruled by a mighty king (Narasimha Raju). His son and prince Jagathalapradhapan (Raja) is a valourous youth who sets out on a mission to capture pirates in the sea. He lands at Sangu Theevu, where the head of the sea pirates Alai Kallan lives. Jagathalapradhapan comes across Mohini (Namitha), who belong to the local fishermen community in the island. Romance blossom between them. Jagathalapradhapan manages to nab Alai Kallan and decides to return to his country. He promises Mohini that he would bring his parents to arrange for their wedding. However the King and his wife Mangayarkarasi (Yuvarani) arranges for their son’s marriage with a princess Azhagu Nachiyar (Nila). Jagathalapradhapan tries hard to convince his parents that he would marry only Mohini.