The film begins with newly elected Lalgudi Karupaiah Gandhi (LKG) swearing in as Chief Minister (CM) of Tamil Nadu, where he is shot in the chest by a sniper.

The story moves back to six months ago where LKG is a mere councillor from Lalgudi ward in Trichy rural and belongs to the ruling party. LKG aspires to quickly achieve big in politics, unlike his father Azhagu Meiyappan, who neither achieved fame as a politician nor made money. The incumbent CM and ruling party chief, Avudaiyappan Mudhaliar, falls ill and gets hospitalised, while Bojappan, the party general secretary, becomes the interim CM. Since Avudayappan is the MLA from Lalgudi, LKG decides to put all efforts to contest in the by-election on behalf of the ruling party, once Avudaiyappan dies.

However, LKG feels that he needs to create some media visibility to get into Bojappan's good books. LKG gets the paid help of Sarala Munusamy aka Sara M. Samy, an employee of V Analytica – a multinational company which is involved in election strategy formulation. LKG goes to Delhi to protest and create an awareness against diseases, which gets the media's attention. Finally, LKG gets Bojappan's attention and meets him at party HQ in Daryaganj. Within a week, Avudaiyppan dies, Bojappan becomes the official Chief Minister, and a by-election is scheduled in Lalgudi constituency. Bojapan urgently announces that LKG is the by-election candidate at the party's general body meeting. Most of the party members and ministers do not agree with Bojappan's decision.

The ruling party's deputy-General secretary Ramraj Pandian, who was in USA when Avudayappan died, comes to the meeting hall. He is furious and feels betrayed by Bojappan's actions. He reminds him that he had been elected as MLA from Lalgudi, his hometown, in a hat trick in last 17 years, and only relinquished the seat due to Avudayappan's personal request in the previous general election. He announces that he will contest in the election as an independent candidate, and once he wins, Bojappan will be expelled from the party and government, while he becomes the new CM.

Now, LKG realises the hardships of contesting in the elections. He understands that people are in favour of Ramraj due to his strong influence, hard work, caste and image. Also most of the state ministers, ruling party bigwigs, and MLAs do not work for LKG as they want to remain neutral to join the victor of the by-election. LKG devises a strategy to tarnish Ramraj's image with the help of meme creators and his sidekicks. He spreads rumours that Ramraj is actually a woman disguised as man, which results in the public trolling Ramraj on social media. Ramraj is also insulted when he is unable to sing "Tamil Thai Valthu" during a college function. Ramraj discovers that V Analytica is behind LKG and strikes a deal with Sara to support him.

Per Sara's advice, Ramraj goes to Delhi and meets national ruling party leaders. He also tries to break the ruling party of Tamil Nadu and prevent Bojappan from trying to take all the party MLAs to a resort. It is revealed that Sara was actually pretending to be on Ramraj's side. She comes back to help LKG, but a tussle comes within the party, while some party senior leaders do not want LKG to gain fame. However, Bojappan is in favour of LKG. During election, LKG wins against Ramraj, but Bojappan gets arrested in corruption cases, and LKG becomes the CM-elect of the state, due to Bojappan's efforts. The next morning, LKG is at the podium to be sworn-in, where he is shot.

The flashback ends, and now it is revealed that LKG was wearing a bulletproof vest during the swearing-in ceremony upon anticipating such an incident. The sniper is a youngster who aspires to some new-gen honest politicians. LKG speaks in front of the media that he is in to bring a change and that he has transferred the corruption cases against Bojappan to the CBI. He also delivers a message that there are numerous educated youngsters contesting in elections independently with a hope of bringing a change but go unnoticed by the public due to big political parties staying in the limelight. The sniper is convinced now, and the entire state believes that LKG will bring some good to the state, unlike other politicians. In the end, Sara smiles upon seeing LKG, which implies that he is just becoming a corrupt politician through his speech trying to woo public which was her strategy as well to win the hearts of people. Also, LKG silently reveals that he never intends to bring Bojappan out of prison.