Sangathalaivan

Shivalingam is a communist representative who leads a trade union, and Rangan is a hard-working worker at Govindarajan's powerloom. Rangan is wary of Govindarajan and his greed. Kalyani, Govindarajan's niece, admires Rangan for his genuine nature. Shivalingam outlines the principles of communism and how they challenge societal greed.

Divya's arm is severed when a loom drags her saree. Govindarajan and Rangan rush Divya to the hospital, where Govindarajan tells Rangan she will regain consciousness and to stay with her. He also orders that the union must not learn of the incident.

Rangan informs Shivalingam at a Communist meeting about Divya's accident. This signals the union's growing involvement in workers' grievances and foreshadows demands that will challenge Govindarajan.

Govindarajan tries to hush the matter by bribing Divya's father with thirty thousand and obtaining his thumbprint on documents. That night, Shivalingam and his men confront Govindarajan and compel him to sign a three-lakh compensation check.

Kalyani confesses her love for Rangan, deepening the personal stakes of the labor struggle. The confession heightens the tension between Rangan's loyalty to the union and Govindarajan's interests.

Govindarajan's nephew informs him that Rangan spoke with the union about Divya's case, and Govindarajan begins to distrust Rangan.

Rangan is beaten by a police officer at the station after a false accusation by Govindarajan's nephew. Shivalingam confronts the authorities and pushes for accountability; Rangan is released after the truth is pursued. Rangan then chooses to tell the truth in court, which leads to Govindarajan's imprisonment.

Rangan moves into Shivalingam's house and joins the union, attending secret meetings to plan upcoming strikes. During this time, Kalyani meets him and hints that he should ask for a share from his family to start a business.

Govindarajan is released from jail as workers have joined the union. He grows angry at the relationship between Rangan and Kalyani and at his family's opposition to that relationship. Despite the opposition, Rangan organizes his sister's wedding.

Shivalingam is briefly arrested by the police but uses the moment to rally the workers and motivate Rangan to lead the strike. Shivalingam's wife goes into labor and gives birth to a girl, which strengthens his resolve to fight.

Rangan leads a strike for the people and rips Govindarajan's shirt as a symbol of protest. The police threaten to arrest him, and he must hide to avoid capture.

Shivalingam is released and goes home; Rangan surrenders to the court and receives 15 days of judicial custody. The collector arranges wage hike negotiations between the union and the owners, and the bosses eventually concede to the union's demands.

Divya informs Rangan that Kalyani has married, marking a personal blow amid the ongoing struggle. The news unsettles Rangan and heightens the emotional stakes around the political fight.

During a gathering, Kalyani overhears Govindarajan and her brother discussing killing Rangan to stop his interference. She notices the danger and Rangan leaves the event early.

A farmer finds Rangan murdered that night, triggering widespread grief in the village. In vengeance, Shivalingam and his men go to Govindarajan's estate, and after Govindarajan's associates escape, surround and kill Govindarajan.