Varnajaalam movie revolves around Sakthivel (Srikanth) enters police officer Devanathan's (Nassar) house by recommendation from a priest. He wins over everyone in the family including the police officer's son, daughter Anita (Kutty Radhika), brother (Thalaivasal Vijay), his wife and their children. But he has a plan of wrecking Devanathan's family. He sends Devanathan's son to a mental asylum and creates conflict between the brothers.
Towards the climax, Devnathan's daughter Anita (Kutty Radhika) corners him and he then tells her father was responsible for the death of his would be Abhirami (Sada) and his family.