En Kadamai(என் கடமை)

Dharmalingam (M.R. Radha), a rich landlord, is the father of two sons and a daughter. His eldest son has a love marriage with a poor teacher's daughter, Kamala,. Dharmalingam disowns them. The son dies and Kamala is left homeless, with a little child. Nathan (M.G.R.), a police officer, gives Kamala shelter in his house and decides to help her fight her case for property. But Kamala is murdered on the way to the court hearing. Fingers point at Dharmalingam and his son Shankar (M.N. Nambiar). Ironically, Shankar and Nathan's sister Uma are in love. Nathan comes to investigate the case and falls in love with Dharmalingam's daughter Sarasu. Now, Nathan is in a dilemma. Should he protect Shankar as he is his sister's sweetheart or should he drop the case as he loves Dharmalingam's daughter. Or is the real murderer someone else?