Surya, the protagonist, is an ordinary insurance agent with an extraordinary problem—he suffers from severe anger issues. During his childhood, his mother Chayadevi helped him manage this uncontrollable rage by making him promise to restrict his anger to just one day of the week. Surya chose Saturday, the same day his mother tragically passed away. Since then, he has stuck to that promise religiously, venting his frustration only on Saturdays and suppressing it for the rest of the week.
Surya maintains a journal where he records every insult, injustice, or grievance he faces, and every Saturday, he opens that journal and settles scores with those who wronged him. He ensures he never acts without moral justification and never crosses the line—unless pushed to the extreme.
Years later, Surya is reunited with Charulatha, a childhood friend who is now a police constable posted in Sokulapalem, a small town under the oppressive control of CI Dayanand “Daya”, a corrupt and violent police officer. Daya harbors a grudge against the town for supporting his brother Koormanand in politics. Driven by personal vendetta, Daya brutalizes the residents with false cases, beatings, and mental torture. Though a constable, Charulatha stands up for justice quietly and helps the townsfolk as much as she can from within the system.
One day, Surya visits Sokulapalem and witnesses Daya’s atrocities firsthand when Daya harasses an elderly woman. It’s Saturday—and Surya intervenes. He allows the woman to escape and punishes the wrongdoers. The town is shocked and inspired by the anonymous vigilante. Word spreads of a "Saturday man" who appears every weekend to right wrongs. This gives the community a ray of hope and a sense of courage.
Daya, however, becomes increasingly paranoid and furious. With the help of SI Sudha, he starts investigating the Saturday vigilante. Meanwhile, Koormanand discovers damning evidence that could expose Daya’s corruption. But before he can act, Daya kills his own brother and frames the murder on the “Saturday man,” turning the police and political systems against Surya.
Surya’s identity is eventually revealed to Daya, and Sokulapalem comes under violent attack. Charulatha is brutally beaten for her association with the vigilante. When Surya learns what happened, he rushes to protect her and the town. But this time, it’s not Saturday—he faces a moral dilemma.
Surya’s father Sankaram, who had been absent most of his life, returns and gives him strength. He encourages Surya to go beyond the boundaries set by his promise to his mother, saying, “Anger is not the problem—it’s how you use it.” The people of Sokulapalem, inspired by Surya, finally rise up against the oppression.
A climactic showdown unfolds where Surya confronts Daya. After a brutal fight, Daya is subdued. But true justice comes the next morning—Govardhan, one of the townspeople, executes Daya and Sudha in broad daylight, sending a message that tyranny will not be tolerated anymore.
In the end, Surya’s sister Bhadra gives birth to a baby girl, and Surya marries Charulatha. The town is freed from its fear, and Surya, now a hero, realizes that anger, when harnessed for justice, can become a force for good.
