Vazhthugal revolves around Kathiravan, a successful entrepreneur who manages a software company. Kathiravan is an affectionate son and socially responsible too. His company is involved in various social activities.
When his close friend's parents are forced by their daughter-in-law to leave home, Kathrivan decides to marry a girl who will keep his parents happy. While watching a television programme he is impressed by Kayal, a college student from Coimbatore being interviewed on a show.
To a question by the interviewer, 'where do you see yourself in another ten years?' Kayal deviating from the usual clichéd answers replies, "As an ideal wife, mother and daughter-in-law." And during the course of her talk, she attributes her success to her large and loving family consisting of her parents, maternal grandfather, aunts, uncles and cousins. Kathiravan is impressed with her attitude and feels that she is the right life companion for him.
He goes to Coimbatore to woo her. But meeting her in her college does not help. So he takes it as an opportunity when he learns that Kayal's grandfather is on the look out for an interior designer to renovate their traditional home. Posing as an interior designer, he undertakes the job winning the hearts of Kayal and her family members.
When the family comes to know that the two are in love, especially Kayal's grandfather who believes that all love marriages are a failure. However, Kathiravan does not want to marry Kayal without her family's acceptance. How he wins their love is what Vazhthugal is all about.