Prakashraj and Seetha have a son named Surendhar (Prithviraj Sukumaran). Sumathi (Saranya Bhagyaraj) is the daughter of Sarath Babu. Sumathi lived in a palatial house and enjoyed a luxurious life in her childhood. However, her father Sarathbabu loses his textile business in a fire accident and is pushed to poverty.
Seetha moves to the house opposite to Sumathi's house. Her husband and son are still back in their city waiting to finish training. Sumathi approaches her to work as a maid. Seetha becomes impressed at first sight by Sumathi's wise and sensible character and takes her as her maid. After a few days, Seetha comes to know that the house she has moved into, was initially owned by Sumathi's family. She soon gets influenced by Sumathi’s modesty, kindness and good nature. Sumathi also had the habit of writing novels, one of which she shared with Seetha. Seetha imagined her son and Sumathi as the characters in the story, which gave her the opportunity to react differently. Assuming that her son and Sumathi are fictional characters in the story, she expresses her desire to make Sumathi her daughter-in-law. At first Sumathi is shocked, but later accepts her request happily.
Seetha communicates this arrangement over the phone to her husband (Prakashraj and son (Prithviraj Sukumaran), that she has chosen her daughter-in-law. However, she did not reveal the name or identity of Sumathi, because she wants it to be a surprise when they meet her in person. Unfortunately, Seetha dies in an accident before the arrival of her husband and son, which leaves a suspense to who the daughter in law is.
After his mother's death, Prithiviraj vows to locate and marry a girl identified by her mother. Since Sumathi is a maid in the house and is much poorer compared to Seetha's family, she does not reveal that she's the one. Bhagyaraj, Prithiviraj's close friend moves into their house to snoop around and find out the girl identified by Seetha. As a father, Prakashraj didn't have the patience and wanted his son to have a good life. This led him to choose a rich girl, completely opposite of what Seetha would have chosen.
Passed many twists and turns, Bhagyaraj finally succeeds in identifying that Sumathi was the girl Seetha chose. His main evidence was Sumathi's published novel, the one she shared to Seetha. Prithiviraj happily marries Sumathi, with the blessings of Prakashraj and Bhagyaraj. The story ends with Sumathi remembering the words of Seetha, that she has always imagined Sumathi to be the wife of her son.