Major Kathiravan is a military official who, with the hope of resuming his job, is working on anger management issues under chief psychiatrist Rathi Devi. Upon hearing his flashback, she counsels him to go to his village and spend time with his father & sister. As a proof, she orders him to upload a picture daily on social media. Kathiravan, who hates his father due to his habit of borowing money , reluctantly does this and posts every picture on Facebook. Soon, he finds out about his sister's love affair and wants to get her married to the lover, but his sister orders Kathiravan to stay away from her personal zone as he was never a responsible brother. Kathiravan realizes his mistake and finds out the truth that his sister's future mother-in-law demands them to bear the marriage expenses which will cost around 10 lakhs totally. He promises to fulfill his sister's wish.

Kathiravan returns to Chennai and tries applying for a loan in every bank. But to his dismay, it gets rejected everywhere. With the advice of his uncle, he takes his father to Chennai along with him and tries to get a loan in his father's name. They gets rejected everywhere as they don't have any financial security with them. To their surprise, they get approached by a man who claims to be a loan agent and tells them to forge documents stating that they are starting a Xerox cum computer shop business in Ambattur and that he will help them in getting the loan. In return, he demands a cheque of INR 60,000 after the first due is over. Kathiravan initially refuses, but as his father urges him, he reluctantly agrees to the man's offer and submits all the original documents to him. The man helps them in obtaining a loan of 6 Lakhs INR.

Initially, Kathiravan is overjoyed and starts the marriage preparation. He gives the ATM card to his dad as it's in his name. His uncle teaches his father how to use ATM. Later on, when his father is unable to withdraw money due to insufficient balance, he informs Kathiravan who in turn is shell-shocked to know about the missing fund. He checks his dad's phone. To his surprise, no SMS is received on his phone regarding withdrawal from the bank. Kathiravan enquires the bank staff in a futile effort and as his father asks him if they could borrow money from another bank, he gets frustrated and scolds his father for making him do something illegal. Unable to bear the words, his father attempts suicide. In the hospital, Kathiravan comes to know that his father took debts to extend Kathiravan's sick mother's life. He feels remorseful after hearing this and starts loving his father. On Rathi Devi's advice and with help of his teammates in the military campus he decides to the track down the culprit.

Kathiravan manages to apprehend and chase a loan agent who had similar terms to Kathiravan's loan agent in order to extradite some information. He gets a phone call from a mysterious number who tells Kathiravan to release him; he tells him he knows all details about Kathiravan and even threatens to release the private audio and video of his sister's phone on the Internet. Upon hearing this, Kathiravan gets shocked and decides to leave the agent who gets fatally hit by a van. The mysterious person is later revealed to be Sathyamoorthy, aka The White Devil, a cyberterrorist and the kingpin of Dark Net and also known as the Digital Don with an aim to know the information of every person in the country. He runs an educational trust named Amara Jothi Institutions and cons people from all walks of life who are in need of money. Kathiravan fights an entire gang of his henchmen and further, through various methods, gets to know about the next victim conned by the same agent and confronts him. He also comes to know how White Devil blocked all the bank messages with the help of his henchmen hackers. When Kathiravan finally confronts Sathyamoorthy in a ceremony where he is about to be felicitated by UNICEF, the latter reveals his knowledge of the former following him since he was captured on a selfie posted on Facebook and attacks his sister through his strong networks. Sathyamoorthy also tells Kathiravan that he put 10 Lakhs to his account which was used by terrorist groups. Kathiravan afterwards is court martialised and is dismissed from his post due to White Devil releasing an information on those who took loans using forged documents, including Kathiravan's, to the media. Still, with the help of Rathi Devi, he tracks and fights White Devil's henchmen. Through hacking, he transfers the Tamil Nadu Police's Money into The White Devil's account. At a dock, the two finally engage in a fist fight. Sathyamoorthy burns the money thinking that it won't be repaid now but to his astonishment the money which he burnt belonged to the Minister whom he struck a deal with. All the people who were conned by Sathyamoorthy come to know about the theft through messages sent by Kathiravan through WhatsApp, and they reach the dock. Kathiravan leaves Sathyamoorthy at the mercy of the crowd and then blends in with them. The affected people, including Kathiravan, soon get their money transferred back to their respective accounts and their bank messages get unblocked. Meanwhile, Sathyamoorthy is arrested by the police but creates a new username named Dark Angel via his smart watch and giving an evil smile implying that he will return.