Chotta is a ruthless terrorist who has toppled security in the past and is currently imprisoned in Uttar Pradesh. He orchestrates a dramatic escape by planting a bomb in the prison, then moves across India, striking in cities and leaving a trail of casualties. His next target is Chennai, and the city becomes the stage for his chilling mission. On the road, he rides along in various vehicles, taking lifts and continuing to plant deadly devices. He coordinates with his associates through a Gmail account, composing messages and saving drafts for later, sharing login details with his team so they can log in and delete drafts after reading. By doing this, their digital footprints stay hidden and untraceable. As the danger grows, the police issue a nationwide red alert, distributing Chotta’s photo to every station, and the search for him intensifies.
Madhusoodhanan, or Madhu, is a jobless software engineer hit hard by a recession. He is secretly in love with a wealthy young woman named Bhargavi, whose elder brother, Dheena Sebastian, works as an ACP and openly dislikes Madhu. The couple dreams of a registered marriage, a plan Bhargavi pushes them toward before Dheena can intervene. Facing unemployment and mounting debts, Madhu borrows money from a notorious moneylender, Kanthuvatti Murugan, and finds himself struggling to repay. This adds tension to a relationship already strained by social and religious divides. On the eve of their planned wedding, Madhu borrows a friend’s car, promising to return it soon, and this choice will soon entangle him in a far larger danger.
Kulandai Velu, a dubbing artist who voices Chhota Bheem in Chennai, lives a simple life with his wife who awaits news back home as she prepares to welcome their child. Late one night, he heads toward his own native place on his motorbike, promising to return after finishing his day’s work. On the highway, he encounters Chotta and stops to give him a lift, even lending Rs. 200 to buy fuel. They pass a police check post, and Chotta quickly vanishes when he senses trouble. Later, a misstep at a petrol bunk leads to a confrontation where Chotta is knocked unconscious and ends up in Madhu’s care at a hospital. Madhu borrows time and money to leave the hospital, while Chotta escapes to a hidden flat in an apartment building.
A doctor who treats Chotta learns the terrorist’s identity from the news and informs the police. CCTV footage from the hospital and the highway shows Madhu and Kulandai providing lifts to Chotta, and the authorities quickly detain both men. While in custody, the two are badly injured in a jeep accident, which causes Kulandai to lose his memory. Madhu grows suspicious that Kulandai might be connected to Chotta, and Dheena sees Madhu as a possible collaborator, planning an encounter. Madhu and Kulandai manage to escape with Bhargavi’s help, and they hide in a flat below Chotta’s lair, in the same apartment complex. Chotta schemes to strike in two days and begins sending the locations to his associates via drafted messages.
In a bid to recover Kulandai’s memory, Madhu and Bhargavi take him to Dr. Thillai for hypnotherapy. The treatment brings back his memory, revealing that he is not an ally of Chotta’s either. With Kulandai’s recall, they discover that Chotta had given him a lift and used lip-reading to capture the Gmail username of Chotta and his cohorts. Although the password remains unknown, Madhu works with a telecom friend to trace the number to the same apartment where they are staying. Madhu identifies Chotta and captures him, but the terrorist fights back and escapes in a car with his female associate.
As Madhu chases, he records a crucial conversation between Chotta and his partner. Chotta issues a new set of instructions to the bombers through a draft in Gmail, detailing the locations to be attacked. Madhu retrieves Chotta’s laptop and brings the fight to the police commissioner’s office. Dheena corners them but ends up learning the truth: Madhu is not the enemy. With the password extracted from Chotta, Madhu logs into Gmail, opens the plan, and discovers that the drafts were scheduled to be checked only one hour before the attack. Madhu deletes the drafts and sends a refreshed set of location details to all four bombers, directing them to a single meeting point.
The bombers head to a bus, only to find it populated by undercover police ready to detain them and disable the bombs. The city is saved, and Madhu is hailed as a hero for his quick thinking and courage. Dheena finally approves Madhu’s relationship with Bhargavi, and the couple looks toward a future together, with Madhu even planning his dream home. Yet the closing arc reveals a darker turn: as Dheena and his officers transport Chotta along with the bombers to jail, they contemplate a violent end for all of them, signaling the continuing, precarious line between duty and justice.
