A dam in the village of Solaiyur, which is the lifeline of that village is under assessment for structural integrity by the Public Works Department. The dam inspector (Ponvannan) assesses that the dam is still strong 75 years after it was built. Later that evening, he is hanged to death by the corrupt local MP Nagabhushan (Jagapathi Babu), who wants the dam destroyed for his own benefit. The dying dam inspector throws a pen drive containing details about the proposed plan to destroy the dam into an abandoned Shiva temple near the dam and warns the village head Karunakara (K. Viswanath) that the temple has to be opened as soon as possible, after which he passes away. Karunakara and the villagers are of the opinion that the temple can only be opened by the descendant of Raja Lingeswaran (Rajnikanth), who built the dam as well as the Shiva temple. Lakshmi (Anushka Shetty), the granddaughter of Karunakara and a television journalist, goes on a search to find the Raja's descendant. She soon manages to find the descendant, whose name is Lingeswaran aka Lingaa . Lingaa is the grandson of Raja Lingeswaran, but is a petty thief with his family having now fallen on hard times. He holds a grudge against his grandfather, feeling that he had brought down his family into poverty by squandering all his wealth and hence refuses to go with Lakshmi to Solaiyur. However, Lakshmi implicates Lingaa in a robbery, as a result of which the police pursue Lingaa. Lingaa is forced to accept Lakshmi's invitation to avoid getting caught and travels with her to Solaiyur.

At Solaiyur, Lingaa finds out that the Lingam installed at the Shiva temple is made of Maragatham stone (Emerald), which is extremely valuable, so at midnight, he enters the Shiva temple with the intention to steal the Lingam. But he is noticed by one of the dam's security guards named Riazuddin Rony from Noakhali, who immediately alerts all the villagers including Lakshmi, Karunakara and Nagabhushan, to the temple courtyard. Aware of the villagers' presence, Lingaa pretends to perform pooja to the Lingam. This fools the villagers, who find it auspicious that the grandson of Raja Lingeswaran is performing pooja to the Shiva Lingam installed at the temple built by the Raja at on the occasion of Maha Shivaratri. Karunakara then tells everyone present, including Lingaa, the story of Raja Lingeswaran.

Raja Lingeswaran, the very rich ruler of the erstwhile princely state of Kodiyur, the best civil engineer from Cambridge and a civil services officer. He becomes the collector of Madurai district, and arrives at Solaiyur village. There the people tell him that they have no water for 9 months per year, and the other 3 months they have heavy rainfall and floods. They are unable to store water and the resulting famines cause hundreds of deaths every year. Though the collector applies to construct a dam, his plan is rejected in the annual collectors' meeting and he is forced to approve a new railroad from Tuticorin to Kochi through Madurai for goods. He refuses to do so and is blackmailed that he will be fired. He immediately resigns his job and exits.

He invites the provincial governor to his birthday dinner and cunningly gets approval from him, on condition that the dam will be built using his own finance. Though he faces multiple difficulties, the dam is nearly constructed, except for the shaft doors. The doors are being held in custody by the new collector as stolen goods and the floods are soon to occur. The new collector proposes that the king gives him all his property as a bribe and all credit of constructing the dam goes to him and the British government. The king with whole heart does so. The dam is fully constructed in 1939 at Solaiyur to solve the water problems of that village. The British lied to the villagers that the Raja was a British spy who would hand over the dam and all the villagers' lands to the British once the dam was completed. The irate villagers threw the Raja out of Solaiyur. Later, the villagers realised the Raja's true intentions and after a search found him and his wife Bharathi (Sonakshi Sinha) living in poverty. After unsuccessfully trying to convince the Raja to return to Solaiyur, the villagers decided to keep the Shiva temple which was built along with the dam closed until the Raja or his descendants returned to the village. Lingaa, on hearing the Raja's story, changes his opinion about his grandfather and decides to mend his ways.

Later, Lingaa and Lakshmi, through the pen drive hidden at the Shiva temple, find out about Nagabhushan evil plans to destroy the dam. They manage to expose him in front of all the villagers in the climax. The movie ends with Lingaa and Lakshmi, who are now in love with each other, leaving Solaiyur, with Lingaa deciding to return once he has done something good in life like his grandfather.