Engal Anna is the remake of Malayalam movieChronic Bachelor. Vijayakanth loses his father, when he is very young. His father (Lal) and Rajiv were bitter enemies. But when they decide to come together with the marriage of Vijayakanth and Indraja (Rajiv's daughter), their relative Thyagu plays a game by revealing other side of Lal that he has another wife with a son (younger Lal) and daughter (younger Swarnamalya).
Then a plot created by Thyagu kills Rajiv and Lal are blamed for this. Lal gets arrested and eventually dies. Convinced that his father had killed Vijayakanth sets out in search of his younger brother and sister, while Indraja decided to marry Thyagu's son.
Later, Vijayakanth realises the truth. Thanks to his uncle Manivannan, he comes to know that his father had no hand in Rajiv's death and resolves to remain a bachelor all through his life. He lives along with his assistant Vadivel, who too has decided to remain a bachelor.
Vijayakanth sponsors for his sister's studies (not revealing his identity). In the meantime Namitha and four of her friends come to stay at the house next to his house, where Swarnamalya stays. And he too has a few guests in his house, like Pandiarajan and Prabhu Deva (Manivannan's son).