Senapathi is a 60 year-old billionaire in Chennai, god-fearing boss of a powerful crime family, and benami of multiple politicians. While on the way back from a temple with his wife, Lakshmi, to celebrate their wedding anniversary, assassins disguised as policemen, attempt to kill Senapathi and Lakshmi, despite being escorted by heavily armed men. However, they escape the assault with minor injuries. Senapathi's children – a daughter and three sons – are notified of this.

The eldest son, Varadharajan, runs the bigger part of his crime empire, based in Chennai. He is married to Chitra and has 3 children. The second, Thyagarajan aka Thyagu, operates his hawala business in Dubai with Arabs, laundering his father's income. He is married to Renu and has 2 children. The third, Ethirajan aka Ethi, runs the independent Serbian section of Senapathi's weapons empire. He is engaged to Chaaya. Senapathi's daughter, Priya, is married to an industrialist, based in Coimbatore. Thyagu, Ethi and a heavily pregnant Priya, return home, after hearing about the attack on their parents.

Meanwhile, Varadan tries contacting his childhood friend, Inspector Rasool Ibrahim, for information behind the ambush on Senapathi. Rasool has been recently suspended on a human rights violation, by beating a young boy during an investigation, for a case. Soon, after his arrival and meeting up with Varadan, they discuss the attack and about the potential mastermind behind it, with Chinnappadasan, a longtime rival of Senapathi, being the most probable. Although Chinnappadasan denies being the one behind the attack, Varadan kills Chinnappa's son-in-law, creating a gang war by sending a person to shoot Thyagu in the lawn, men to shoot Ethi and Rasool, during a casual football match with his friends, on the beach, and some of his henchmen to shoot Varadhan, which they all miss.

At the same time, Senapathi regains health, and Priya delivers a boy. During their meetup with Chinnappadasan at the new baby's naming function, Senapathi tells him that he is aware of who the culprit is, and makes peace. Senapathi reveals to Lakshmi that one of their sons is behind this. Thyagu and his family leave for Dubai, while Ethi returns to Serbia, for his wedding with Chaaya. Soon after, Senapathi dies from a sudden stroke, and the brothers start a power struggle over who will be the next "king to the throne". A feud begins between them, after Varadan takes control of his father's domestic empire. Further, he conspires against his brothers, by harming their wives and hiring men to kill them. Chaaya is killed by a sniper while honeymooning with Ethi. Renuka is arrested on false charges and imprisoned for life in Dubai.

Ethi and Thyagu join hands to seek vengeance against Varadan, on the condition that, Thyagu will be the sole king over the whole empire. They try to get back to India, via Nepal, but are captured by Varadan's men at the airport. Ethi and Thyagu thrash the men and inform Varadan, before escaping and reaching Chennai. They overpower Varadan, by manipulating his henchmen, promising them higher wages and a better life, overall. They kill their maternal uncle Chezhiyan, who is Varadan's father-in-law (Chitra's father), and capture Varadan's lover, Parvathi. Ethi manages to bribe Rasool into working for them. Fearing that his brothers may harm his family, Varadan sends his family away to Coimbatore and flees from Chennai, with Chitra.

During a night shootout in Andhra Pradesh, Chitra is shot. In the hospital, before she dies, Varadan reveals to her that he hired the assassins to kill Senapathi, so that he could succeed in getting his father's place and take over the empire. Ethi and Thyagu catch Varadan with Rasool's help. In the midst of the confrontation, Thyagu kills Varadan, for framing and incarcerating Renuka. Subsequently, Ethi kills Thyagu, for hiring an assassin to kill Chaaya, after Thyagu revealed that he only did that to create a "spark". Ethi tries to lure Rasool at gunpoint, by offering to either "bite the dust or join him". Rasool stalls Ethi, by narrating how his father, a gangster, was gunned and killed at the Chennai airport, before him and his mother.

Fearing for his life, Rasool's mother sent him to live with his uncle and aunt, before committing suicide. These events filled him with hatred of all gangsters and criminals, and became a cop, as a result. He also reveals to Ethi, that he is actually working undercover, to eliminate Senapathi's empire, and the rift between the brothers created a chance for him to bring down their empire of crime, once and for all. Rasool then proceeds to shoot and kill Ethi, before reporting to his superiors, that Operation Red Sky has been accomplished.