Orphaned at a young age, Kali and his sister Valli grew up on the streets and were street performers. Kali played the drums and Valli perched herself atop a pole balanced by an older boy. Kali frequently gets angry at people whom he thinks lack empathy for the socially or financially deprived. As adults, the siblings live in a hilltop village where Kali works for a powerhouse in the valley below. From a shed in the village, he operates a winch for a cable trolley which ferries employees to work. The powerhouse's new divisional engineer, the rule-abiding but fair Kumaran, notices Kali offering free rides to unauthorised townspeople. When he orders the passengers out, citing rules of operation, Kali becomes angry and stops the trolley half-way downhill. Kumaran shrugs off this act with a knowing smile.

On a nearby canal's bank, Valli meets a young woman, Manga, who, along with her mother, has arrived from a drought-stricken town, Ilaiyangudi. The mother is looking for work, and both women are hungry—Manga ravenously so, a fondness for food becoming one of her primary characteristics. Valli feeds and shelters them for the night, and asks Kali about allowing them to use the vacant house next door. Meanwhile, Kali roughs up his fellow employees whom he suspects of snitching on him to Kumaran. Kali is given a final warning by Kumaran as a prelude to serious disciplinary action.

While Kali is at work, Manga appears, picks up his watch and teasingly declares she will run away with it. A chase ensues, taking them through the woods and into the river. Waist-deep in the water, Kali retrieves the watch and rushes back to the shed. During his absence, a child living in the valley has needed medical attention. After the emergency alarm at the shed has rung for several minutes, a passerby steps in to operate the winch. The child is transported back in the trolley and dispatched to a hospital. The following day, Kumaran suspends Kali from his job for ten days for gross misconduct.

That evening, Kali goes to the nearby Mullimalai to assuage his anger at Kumaran among the Badagas, joining them in singing and dancing. While staggering back home drunk, Kali passes out on an unlit street. A truck drives over his left arm, which is amputated at a city hospital. As a result, Kumaran regretfully fires Kali since he can no longer perform his job adequately with one arm. At Valli's prompting, Kali and Manga agree to marry; they have a simple wedding ceremony held at the local temple. Kumaran attends and brings a present of cash, which Kali rejects, but Manga accepts.

Kumaran becomes attracted to Valli. After determining her willingness for marriage, he requests permission from Kali who asks him to return the following day. Later that day, Kali corners Murgesa, a local grocer who is known for flirtatious behaviour, and offers him his sister's hand in marriage. An engagement ceremony for Murgesa and Valli is arranged. At the ceremony, Manga angrily interferes in the main ritual, which makes Kali furious at his wife. He physically assaults her repeatedly, but Manga remains firm in her opposition.

The next day, Manga convinces Kumaran and Valli to marry without Kali's knowledge, but he accosts their wedding party on its way to the temple. Kali accuses his sister of abandoning him because of his handicap. Valli is filled with guilt and rushes into his arm. Kali reminds the onlookers that he remains the most important man in his sister's life. Although he still dislikes Kumaran, Kali's self-esteem is restored, and he offers his blessings for the marriage.