In Alanganallur, Arunachalam, a respected young headman, shares a home with his parents, Ammayappan and Janaki, along with three younger siblings—Saravanan, Sakthivel, and their sister Arundhati—while their stern grandmother, Vedhavalli, guards the family lineage with unyielding pride. As Arundhati’s wedding draws near, Ammayappan’s estranged sister, Umayal, returns with her own family. Vedhavalli once disowned Umayal for marrying Aathikesavan, and Umayal’s teenage daughter—also named Vedhavalli and named after her grandmother—watches Arunachalam with a growing admiration. Umayal and Aathikesavan begin to dream of a reunion by arranging Vedhavalli’s marriage to a cousin, hoping to stitch the family back together.
At Arundhati’s nuptials, the rival elder, Chokkalingam, tries to derail the ceremony. He forces Arundhati to marry his son, Ponnambalam, on the basis of a document allegedly signed by Ammayappan. Yet, Arunachalam steps forward to thwart the move and ensure Arundhati’s wedding proceeds as planned, defending the girl’s happiness even at personal cost. The tension between tradition and truth deepens as the wedding ritual unfolds, and the village begins to see the strength of Arunachalam’s conviction.
In the aftermath, [Vedhavalli] falls in love with Arunachalam, even as the elder Vedhavalli resists the match. At the village panchayat, Sakthivel is accused of deceiving a poor girl, a charge he denies, refusing to marry the girl due to her impoverished background. Arunachalam, who has observed Sakthivel’s closeness to the girl, offers a radical remedy: he proposes to relinquish his own share of the family property to the girl to win Sakthivel’s acceptance. But the grandmother intervenes with a revelation that shakes the foundation of the clan: Arunachalam is an orphan, adopted by Ammayappan and Janaki, who were childless. The truth deepens when it is revealed that Meenakshiyammal, Arunachalam’s biological mother, handed over her newborn son to Ammayappan on her deathbed. With this knowledge, Arunachalam leaves the village for Madras, seeking his own path and purpose.
In the city, Arunachalam meets Beeda Kathavarayan, who offers him a job and soon befriends Nandhini, daughter of the honorable Rangachari, a businessman who controls Vedhachalam’s vast wealth. Rangachari and four other magnates oversee properties valued at Rs. 3030 crores, yet Arunachalam remains unaware that Vedhachalam is his biological father. He stumbles upon a secret meeting where the money is about to be siphoned away by the fraudulent quartet Vishwanath, Kaliyaperumal, Prathap, and Kurian. Rangachari recognizes Arunachalam as Vedhachalam’s son and rightful heir. A video left by Vedhachalam reveals the conditions for inheriting the fortune: Arunachalam must spend Rs. 30 crores within 30 days, refrain from donations, not hold assets at the end of the period, maintain utmost secrecy, and produce receipts for every expense. If he fails, the wealth will pass to a trust.
Initially, Arunachalam contemplates surrendering the wealth to the people, honoring his father’s apparent wish. Yet, after overhearing the conspirators’ plans to siphon the fortune for themselves, he accepts the challenge. A bold spending spree ensues: he rents a five-star hotel, commands luxurious cars, participates in horse racing, buys lottery tickets, and even backs a film project with his friend Arivazhagan as the lead actor. The four corrupt men retaliate by dumping money into obstacles designed to thwart him. Undeterred, Arunachalam even launches a political party, with Beeda Kathavarayan as the MP candidate, demonstrating his commitment to a higher cause than mere wealth.
As the 30-day deadline looms, he dissolves the party and has Kathavarayan resign, a move that strains his relationship with Vedhavalli because he cannot explain the source or purpose of his financial choices. Vedhavalli suspects he has changed and agrees to a marriage proposal from a friend of Aathikesavan’s to settle debts, even as Arunachalam finds it hard to reconcile his mission with personal love.
With the end in sight, Arunachalam completes the spending requirement and proceeds to Rangachari’s office to sign the documents. In a final — and desperate — act, the rivals push for only Rs. 20,000 at the last moment. Arunachalam uses that scant amount to pay Nandhini’s salary, thereby satisfying the terms and becoming the rightful heir to the Rs. 3000 crore fortune. He entrusts Rangachari with stewarding the wealth for the public good, and the villains press their assault to reclaim what they cannot have. Arunachalam defeats them in a climactic showdown, and in a decisive public moment, Rangachari publicly confirms Arunachalam’s selfless mission.
Moved by his integrity and desire to do good, Vedhavalli opens her heart to him and accepts him as her grandson and rightful heir. The couple’s bond deepens as Vedhavalli comes to understand the truth of his character, echoing a shared conviction that wealth must serve the people. In the final, heartfelt reconciliation, Arunachalam and Vedhavalli marry, sealing a future in which family, forgiveness, and social responsibility intertwine.
