Raghav wakes up severely injured in a hospital. The next scenes form a flashback to events that took place several weeks previously.
Azhagar, the CEO of an online taxi company, wins an industry award. Vinayak Kanakasabai, a rival CEO, challenges him that his company, GoCabs, will ovetake Azhagar's company. Azhagar orders his assistant Pugazhendhi to do something to stop this. Pugazhendhi hires criminal suspects to commit crimes in GoCabs taxis as drivers, and news of these incidents goes viral, leading to a police investigation and a lawsuit against Vinayak.
Raghav is a talented boxer who lives with his father, Chandramouli. He seeks sponsorship from Azhgar for a major fight, but is rejected; he then approaches Vinayak and is successful in securing sponsorship. Raghav wins and gives the prize, a new car, to his father. Moved by the gift, Chandramouli invites him out for a drive at midnight. The car is run over by a truck, killing Chandramouli and severely injuring Raghav.
Upon waking up in hospital, Raghav learns that his father died and that his nervous system is incurably injured, severely restricting his vision. Several days later, an officer calls at his house with Chandramouli's signature on the death certificate of a woman named Bairavi. Raghav, his girlfriend Madhu, and his friend Padmani initially tell the officer that he has the wrong house, but after reviewing the papers, Raghav confirms that the signature is his father's. It transpires that his father hosted Bairavi's funeral days before his own death, because he was the only person connected with her.
Chandramouli's close friend Ramamurthy confirms that Bairavi, a single woman with no children or parents, was Chandramouli's friend. They got to know each other when she tried to buy his car at a high price because it reminded her of her deceased father, who had the same car. She also helped Raghav get Azhagar's sponsorship because she was the financial manager of Azhagar's company. Bairavi was then apparently killed by a GoCabs driver. However, Chandramouli told Ramamurthy that Bairavi was not killed by the driver, but by someone else he knew. He asked Ramamurthy's help to reveal the truth, so Ramamurthy took him to a senior police officer to report it. The officer warned him not to get involved in this case because important people were behind it. Chandramouli is seen confused on his final day, when he asked Raghav for a late night drive.
Raghav finds and confronts the driver, who tells him that he accidentally lost control over the vehicle. However, Raghav later overhears the driver speaking to Pugazhendhi about their conversation, and chases him, only to find him hanging dead in an isolated factory. Later, Padmani informs him about Bairavi's phone found in Chandramouli's car, which contains evidence of Bairavi's murder. To find out who the murderer is, Raghav plots to trap the next murderer from GoCabs and sends Madhu and her colleagues in GoCabs. Everybody reaches their destination safely except Madhu, who alerts Raghav when the cab driver stops the car in a remote area. Raghav arrives in time to catch the driver, who confesses that he was instructed by Pugazhendhi to do so. Raghav finds Pugazhendhi in a bar and chases him, but he escapes. The next day, he is found dead after he uploads a video of his confession about the murders, blaming Azhagar. Raghav then visits Vinayak, who it turns out is the real culprit. Raghav fights with Vinayak and finally burns him to death. The next day, news channels report that Vinayak had escaped, no one knows his whereabouts, and police are searching for him.
Finally, Raghav is seen smiling happily in Chandramouli's restored car.
In early October 2017, director Thiru announced that he would be making a film starring Karthik and his son Gautham Karthik. Produced by G. Dhananjayan, Thiru revealed that the film would be an action thriller where Karthik would portray a government official and Gautham would portray a boxer.[3]Regina Cassandra and Varalaxmi Sarathkumar were signed to portray the lead female roles, while Sathish was cast in a further supporting role.[4] Thiru also cast veteran directors, Mahendran and Agathiyan in pivotal acting roles, with the latter being the director's father-in-law.[5]
After a period of deliberate suspense, the team announced that the film would be titled Mr. Chandramouli. The film's title is borrowed from a dialogue spoken by Karthik in Mouna Ragam (1986).[6] Production began in late November 2017, and continued throughout early 2018.[7][8]
The soundtrack album of Mr. Chandramouli consists of 6 songs composed by Sam CS and was released on Sony Music on 25 April 2018.[13][14] The title track was co-sung by actor Sivakumar's daughter Brindha, who made her playback singing debut with this film.[15]
