As Sivaji Sontineni plays Gopalam, the zamindar of Appapuram, he establishes a high school named after his elder daughter Mahalakshmi. As a child, Mahalakshmi went missing during a pilgrimage in Kakinada. The school soon suffers from mismanagement by Gopalam's nephew A. K. Raju, an amateur detective, and Panthulu, an ayurvedic doctor and teacher who uses students to prepare medicines. To turn things around, Gopalam decides to replace them with a married pair of graduates, hoping they will also train his younger daughter Sita in traditional music and dance.
Mahalakshmi was found and adopted by a Madras-based Christian couple, Mr. and Mrs. Paul, who named her Mary. After graduation, Mary searches for a job to ease her family's finances. Her father had taken a loan from I.P. David, a loan shark, and David now offers to waive the debt if she marries him. To repay the debt, Mary agrees to a plan proposed by another unemployed graduate, M. T. Rao, whom she meets at a job interview. They pretend to be a married couple to qualify for positions at Gopalam's school. Devayya, who finds clever ways to beg for money, befriends Rao and accompanies them to Appapuram as a helper and cook. They are given a modest home behind Gopalam's bungalow.
Gopalam and his wife treat the couple as their daughter and son-in-law. Unaware of her own identity, Mary finds the attention stifling and, while she may find Hindu customs unfamiliar, she says little to Gopalam and his wife because she needs the job to repay David. She quietly vents to Rao, who endures it with patience. Sita comes to the couple for music lessons and innocent attempts to attract Rao's attention further rattle Mary, who also begins to feel romantic stirrings for Rao.
In desperation, Mary decides to tell the truth to Gopalam and his wife. To save their jobs, Rao fabricates a story that Mary is possessed by the soul of Mary, mother of Jesus. When Mary hints that she might leave Rao, Gopalam threatens to offer Sita as a bride to Rao. Raju, Gopalam's nephew who loves Sita, wants to keep Rao away from her and enlists Mary to help in teaching music, which ends in disaster. At the end of their first month, Rao and Mary receive their salaries and Mary repays her debt.
Raju grows suspicious that Mary is the missing Mahalakshmi. After Gopalam's wife reveals that Mahalakshmi bears a mole on her right foot, he and his assistant Govindan sneak into Mary's room at night to verify, but the plan backfires when they wake her. A dream in which Rao rescues her from David strengthens Mary’s feelings for Rao.
As Sita continues to insist on music lessons from Rao, Mary’s irritation grows, and she contemplates returning to Madras. Rao initially asks her to stay, but as the situation escalates, he tells the Gopalam family that Mary is going to Madras to visit her ailing parents. The Gopalam family misunderstands and believes Mary is pregnant; they host a seemantham and Mary remains confused. The night before her departure, Rao pretends to have a broken leg to delay her leaving. David arrives and tells Raju that Mary, a Christian, is posing as a Hindu for the job. Raju retrieves a necklace that David had stolen from Mary’s home in Madras—the same necklace that Mahalakshmi wore when she disappeared.
David wants to marry Mary, but she declares her love for Rao. The Pauls arrive, and Raju pieces together the truth, leading to David’s arrest. Although Mary learns that Gopalam and his wife are her biological parents, she affirms her bond with her foster family. With Rao and Mary not yet married, Gopalam announces their wedding and also the marriage of Sita to Raju.
