Dharmathin Thalaivan

Balu is an absent-minded but kind-hearted college professor who leads a simple, compassionate life. He shares his home with his younger brother Raju, maternal uncle Rangarajan, and his cousin Sumathi, who is also his love interest. The household dynamic centers on Balu's care and the tensions that arise from Raju's unruly temperament and Sumathi's affection for him.

Raju is hot-tempered and frequently clashes with a fellow student, Raghupathy, who is the college owner's son. Balu's attempts to reform Raju fail, highlighting the strain between duty, family loyalty, and personal temper. These fights set the stage for the tragedy to come.

One night, Balu intervenes in a fight between Raju and Raghupathy and is accidentally killed. His death is a turning point that shatters the family and propels Raju toward change. The incident marks the beginning of the story's emotional upheaval.

Before dying, Balu asks Raju to ensure Sumathi finds a husband who can care for her, so she will not suffer after his death. Raju accepts this heavy responsibility with a resolve that foreshadows the changes to come. The moment seals the vow that drives the rest of the narrative.

Raju embraces his brother's plea and vows to control his anger and abstain from drinking. He commits to a path of reform and to support Sumathi's future happiness. The vow marks a shift from self-centeredness to responsibility.

Sumathi is devastated by Balu's death and retreats into depression, even donning the garb of a widow. She vows never to marry, becoming detached from the family she once cherished. Her pain tests the remaining bonds and motivates the next phase of their lives.

To help Sumathi move on, Raju and Sumathi relocate to Bangalore, where Raju takes a job at a garage owned by Devi. The new city presents both danger and opportunity as they start anew.

At Devi's garage in Bangalore, Raju encounters Shankar, his brother's doppelgänger, who steals cars and unsettles him with the striking likeness to Balu. Raju finds it hard to fight Shankar and struggles to bond with him because of the resemblance. The encounter shakes the uneasy peace of their new life.

Shankar is moved by the story of Raju and Sumathi and reforms his ways, becoming a police informer. He then falls in love with Sumathi, but she cannot forget Balu and rebuffs him. Her reluctance adds tension as he tries to prove his change.

Bhaskar, a smuggler who once employed Shankar, kidnaps Sumathi to force Shankar to smuggle diamonds. Shankar reluctantly agrees to protect her, knowing the danger she faces. The rescue becomes a turning point that tests loyalty and love.

A climactic fight pits Shankar and Raju against Bhaskar, ending with Bhaskar's arrest and Sumathi's safety. The brothers' alliance strengthens as Shankar's new role stabilizes their fragile circle. The triumph is bittersweet as Balu's memory looms over the events.

In the finale, Sumathi and Shankar marry, and Raju and Devi also wed, uniting two couples and sealing the new family. To honor Balu's memory, Shankar dresses up like the late professor for the wedding, providing a poignant link to the past.