Ramu, Kamal Haasan, is an orphan who is adopted by a wealthy family after he saves them from a deliberate poisoning attempt. Raised by Rajalakshmi, he grows up as part of the family and becomes the steady, loyal presence that helps manage the household. He is seen as a son by the parents, and his devotion to the family remains unwavering even as others outside the unit view him as a servant.
Ramu quietly keeps the family running smoothly and cares for his adopted brothers and sister as if they were his own. While he stays faithful and grateful to his adoptive parents, jealousy simmers among some of the other family members who resent the privileged position he appears to enjoy. The dynamics inside the home become tense as the brothers chase pleasure and an easy life, often attempting to exploit Seetha, the worker whose mother Muniyamma is the cook.
Ramu intervenes whenever mischief arises, trying to steer his brothers toward resourcefulness and responsibility, but his counsel is not welcome. They resent his influence and grow irritated when their mother sides with him in key decisions. In a separate threat to the family’s safety, Ramu also helps protect his adopted sister Rekha from an attempted marriage arranged by Banuprasad, a powerful, unscrupulous figure whose son wants to marry Rekha for his own gain.
Banuprasad’s anger peaks when Rajalakshmi refuses the marriage proposal for his son. He becomes a sworn foe of the family and collaborates with Nagalingam, the corrupt government official in-law, to undermine them. The conflict escalates as Banuprasad hatches a dangerous plot to crush the family’s fortunes and reputation.
The danger intensifies when Banuprasad plants illegal explosives in Rajalakshmi’s fireworks factory, aiming to arrest her on trumped-up charges. Ramu rushes to her defense, accepts the crime to shield her, and ends up taking the blame and going to jail. His absence leaves the household vulnerable, especially when Rajalakshmi falls ill and her own sons neglect her, squandering money on gambling rather than family duties.
With the factory under the control of the rival faction within the family, Ramu’s brothers make poor business choices and drive the once-prosperous enterprise toward ruin. Undeterred, Ramu returns to work, builds his own fireworks factory through hard work and perseverance, and begins to restore the family’s fortunes. He also steps in to prevent a forced marriage that could seal their downfall, ultimately paying for the losses his brothers incurred and saving both his adopted parents and his sister from disaster.
In a poignant turn, Ramu adopts his mother as his own, elevating her to the role of proprietor of the new factory, a gesture that binds the family together and restores a sense of rightful leadership. The climactic confrontation with Banuprasad returns to threaten the matriarch again, as he attempts to murder Rajalakshmi and overwhelm the family once more. Ramu once again rises to the challenge and saves the day, though Rajalakshmi is mortally wounded and dies in his arms.
The story closes on a reconciliatory note. Ramu’s daughter—whom he regards as the daughter he never had but now rediscovers as his own, naming her after his late mother—celebrates her birthday with the entire family gathered around. The family is finally reunified, with Ramu as the head of the household, guiding them forward with the same steadfast, resourceful spirit that defined his life from the moment he saved them as a child.
