Shiva, the universal cop, has left the police department and has returned to his hometown of Cinemapatti. He is brought back in to resolve a crisis. Once the situation is handled, he is asked to join the department by Police Commissioner Yezhusaamy, but he refuses and walks away. P, a dreaded don who poses a threat to society, kills Shiva's wife Priya by using a cell phone bomb. Shiva is forced to rejoin the police department. Meanwhile, Shiva is finding a girl to marry on his grandmother's request. His conditions for a girl are that he wants a loosu ponnu (a bubbly but crazy girl). He sees Ramya and assumes that she is crazy since she went into a mental hospital van. With the help of his friends, he proposes to her, and she accepts his love.

Shiva learns that P has fixed a bomb somewhere by the clues which were given by P's henchman Wasim Khan. Shiva finds that P has fixed a bomb in a bus. He discovers that P has fixed the bomb so if the bus is driven less or more than five kilometers per hour, it will explode. However, Shiva saves the people inside the bus. Wasim is killed by Rithika, P's henchwoman. Shiva then discovers that there was someone in the department who is informing P about their ideas. He discovers and kills Inbashekhar, the mole, and is seemingly suspended.

Shiva realizes that Ramya is not crazy but a psychiatrist, and breaks up with her. His friends advise him that he needs to reunite with her. He decides to, but Ramya has left for America. Shiva also goes there to find her, and they reunite in Central Park. Then, it is revealed that Shiva went on a mission in America so that he could catch P, and that he was not suspended. When the mission is in progress, Ramya is kidnapped and killed by P. Back in Chennai, Shiva is very sad about Ramya's death. His grandmother asks him to take her to the cemetery. She took some promises which were to kill P, marry a beautiful girl than Ramya (the girl he loved and which died), and to give her a great-grandchild.

Shiva sketches a plan to catch P by demonetising 500 and 1000 rupee notes with the help of the government. He goes to a temple to attend his friend Bharath's marriage. There, he meets Gayathri, a lookalike of Ramya, and gets shocked. He proposes to her in the next two minutes when he sees her. The demonetisation forces P to stand at an ATM queue because he had a lakh crores of 1000 rupee notes. Shiva executes his plan perfectly, but P escapes. Shiva catches him at his Kovalam beach resort. He kills him, but P comes alive and becomes the CM-elect of Tamil Nadu.

Bodhi, a saint, calls Shiva and says that P is immortal. The enmity between P and Shiva is for 76 generations. In 300 BC, King Adhiyamaan was ruling Kovai. He appointed Piyaar as the dance teacher of the kingdom, but his dance was demonic. Bharathamuni, another dancer whose dance was divine, wanted to do a dance-off with Piyaar. Adhiyamaan also said that the winner will get a jackfruit, which will give immortality to the one who eats it, and also his daughter Khaleesi will marry him, but Piyaar's henchmen kill Bharathamuni and his grandmother. As a result, Piyaar gets the jackfruit and becomes immortal.

Now, Shiva needs to go to 300 BC to win the dance-off with Piyaar. He gets a time travel watch from a watch mechanic. He goes to 300 BC, wins the dance-off, Khaleesi, and the jackfruit. He then comes back to 2018, and meets P, who kidnapped Gayathri. He reveals that he ate the jackfruit, and P is no longer immortal. He fights with his henchmen while Gayathri sings. Irritated by her singing, P kills her. Shiva also kills P and is arrested.

During the credits, Shiva is released from prison after 25 years. Worried that Shiva's romantic relationships with other women would result in their eventual deaths, his grandmother kills him, revealing her villainous "D" nature albeit being acquitted in the first film.