Janmam movie tells the story of Veerakudi village lies on the border between Kerala and Tamil Nadu. Years ago an orphan reached there, brought by a truck driver who called him Raayar after the name of his truck. His parents were killed as suspected Naxalites. He avenges his parent's death and escapes as a stove away in the truck. It is half way through the trip that the driver realizes the presence of the child.
Today he is known as Devaraayar, and is the owner of a large fleet of trucks. He is involved in all the social issues of the village. His word is law in the village. He uses his trucks usually deployed for smuggling illicit liquor, to supply free drinking water to the parched village. He helps in the education the needy children. Rajani, a girl whom he helps to educate even becomes an IAS officer and the Collector of the District. He marries Valli, the daughter of the truck driver who brought him to the village and gave him shelter.
Devaraayar's power and prestige spread far beyond the confines of the village. Even ministers come seeking his aid. He enjoys the support and patronage of Vaikundam, a minister. It is at this juncture that Kaliyappan gets released from jail. Things become difficult for Devaraayar after Kaliyappan arrives on the scene.