Pughazhenthi Subramaniam is an athlete who lives in Thanjavur. He is a hurdles race champion and has won many awards – even beating the national record in a local sports meet. He and his fellow athlete friends get intensive training from their coach Devaraj to participate in an important sports meet in Kolkata, the winners of which will qualify for the next major national sports event.

A flashback reveals that Pughazh has Glanzmann's thrombasthenia, which prevents his blood from clotting following any injury. If he gets even a small scratch, he might bleed to death. His father Subramaniam is a constable at the local police station who is very protective of him, has high hopes that he will advance well in life, and make a name for himself as an athlete.

Gayathri Venugopal, a college student who lives in Chennai, finds out that her friend is being harassed on the phone every night by a guy. Gayathri decides to take action by calling him up and threatening him in foul language. However, due to a mix-up, she ends up calling Pughazh in Thanjavur instead. The next day, she realizes her mistake and apologizes to Pughazh on the phone. As a joke, he asks her to top up his mobile phone account, and she quickly does so to make up for it. He then pesters her successfully for several days day for further credit for his mobile phone account until he introduces himself and tells her that he will not call and annoy her anymore. Even though they both have not seen each other's faces before, Gayathri realizes that she likes him and initiates their next communication.

The Calcutta sports meet gets unexpectedly relocated to Chennai instead. Hence, Devaraj decides to go to Chennai with Pughazh and the rest of the team a few days early and train there, which was perfect for Pughazh to make plans to meet up with Gayathri. Gayathri's brother Dinesh Venugopal gets involved in an counterfeit money scam and calls the cops on the criminal gang who manufactures the currency notes without revealing his identity. The right-hand man in the criminal gang falls for Gayathri when he sees her. The leader of the gang goes to Gayathri's house to speak to her parents to get her married off to his favorite henchman, but Dinesh intervenes and threatens to go to the police, in the process revealing that he is the one who called the cops on the gang.

The gang decides to murder Dinesh. When the henchmen are chasing Dinesh, he gets a lift from Pughazh, who is on his way to meet Gayathri on his bike, lying to him that his sister is in the hospital. Due to stress, Dinesh forgets to thank Pughazh when he gets dropped off, but the gang members get a good look at Pughazh, thinking that he intentionally helped Dinesh escape. They find Pughazh, who is still on his way to meet Gayathri, and try to beat him up. However, he fights back and beats them up without getting a scratch on him. During the fight, he hurls one of the gang members, who accidentally falls on Gayathri, who is also in her way to see Pughazh. She gets knocked off her scooty, and her side mirror breaks. She calls Pughazh's mobile just as he is finishing off the fight. They both see each other for the first time. Pughazh immediately fall in love with her, but Gayathri believes that he is a rowdy.

Pughazh is still able to get in the good books of Gayathri and Dinesh by seeing them again during Gayathri's birthday. She invites him to his house, where on Gayathri gets more romantically involved with Pughazh. Meanwhile, after further altercations, the gangsters track and kill Dinesh. In retaliation to Pughazh's beating of the gangsters, they beat Devaraj, who tries to get help from the police. The DCP gives a gun to Pughazh hidden from everyone so that he can once for all finish the gangs activities using Pughazh's motivated intentions to save Devaraj. He is tracked again by the gangsters, who try to harm his friends and Devaraj, but Pughazh fights them off and finally kills them with the gun that he has hidden in his shoes. The next day, he enters the competition, but a fake athlete planted by the gangsters earlier inflicts a cut on his arm. He still runs through the hurdles and ends up unconscious as he crosses the finish line. The final tally shows him winning the hurdles race in a photo finish ending by .01 seconds. The final scenes show Gayathri as his wife watching Pughazh winning the gold medal in the Asian games, following which he also gets the post of DSP in Thanjavur.