An erstwhile naval officer, Vijay singh was disgraced and branded a coward for abandoning his ship during a storm. He now works in a coal mine to do penance for his shame and guilt. As a mine worker, he comes to be known for his selfless acts of courage that help save many lives in the mine.
Mangal is a dacoit who escapes from prison and disguises himself as one of the workers. Ravi is a young engineer who has been employed by Dhanraj Puri, the owner of the mine. Dhanraj Puri only cares for his investments and profits and is willing to endanger the lives of his workers to extract more coal from the mines. Ravi stands up to him, and soon becomes a rallying point for the workers. He also saves Vijay’s life when he gets into a tussle with a fellow worker.
Dr Sudha Sen is an idealist who takes over the clinic in the mines to help the needy. She grows close to Vijay and learns of his infamy. Mangal is attracted to the peppy jewellery seller Channo. He saves her from a few workers who attempt to rape her one day. An old friend of Ravi’s, the journalist Anita also arrives at the mines to report on the situation there. All of them brought together due to their opposition to Dhanraj’s oppressive regime. Though there is some friction between Mangal and Vijay, this is resolved when Vijay donates his blood to help Mangal with an injury. Together, they foil each of Dhanraj’s attempts to break up the workers’ unity.
Ravi’s fears about Dhanraj Puri’s reckless mining come true. One day the mines are flooded with water and many workers including Ravi are trapped inside. Vijay and Mangal fearlessly enter the mines to save them. After a tense sequence, the collective efforts of the workers save the day. Mangal unfortunately loses his life trying to save the lives of others. As Vijay emerges from the mines, he is greeted by his parents who absolve him from his guilt.
The story was based on the 1975 Chasnala mining disaster. The film did average business in the box-office but was a big critical success. It received eight Filmfare Award nominations.