Constable Siva is assigned to escort a witness from police custody to the courtroom. As a twist in the plot, Siva learns that the entire police department wants the witness dead and starts the real run.

An IAS Officer disguises himself as a vegetable vendor in order to nab down a highly potent criminal.

The film begins in a city in Andhra, where the CBI raid a rich local politician’s house. The Chief Officer is shown to be Aadhi (Jayam Ravi), who orders to seize all illegal items found. The politician is arrested, but he requests to come to the CBI office in his own car. It is later revealed that no CBI raid was planned on his house and all that happened was a hoax. The politician gets angry and orders to hunt down the men who cheated him in the name of CBI.

The film starts with Dhivakar (Vincent Asokan) and his family celebrating his birthday. A sudden lightning strike kills him and his son. At a movie theatre, a man gropes a woman, and a small commotion ensues, which was stopped by ACP Paul Dhanarajan (Aadukalam Naren). The plot shifts to detective Kaniyan Pongundran (Vishal), who lives with his associate Manohar (Prasanna). They both come across Mallika (Anu Emmanuel).
One day, a schoolboy Naveen (Master Nishesh) visits Kaniyan and Manohar with a case that his pet Pomeranian Nemo was shot dead and asks them to find the killer. Naveen gives them the bullet from Nemo’s body. Kaniyan finds that it is a 9mm bullet which had been ricocheted from Nemo. At the crime scene, he finds a tooth, with which he tracks its owner as Swarnavel (Ashvatt). Meanwhile, Kamalesh (John Vijay) visits a travel agency to deliver a sofa stashed with money to five members who run the agency: Devil (Vinay Rai), Muthu (Bhagyaraj), Pritha (Andrea Jeremiah), a stout man (Dheeraj Rathnam), and a bald man (Siddhanth Venkatesh).

Jani, a slum boy, loves Sandhya but doesn’t express his love because she sees him as her friend. Jani selects a groom photo as per Sandhya’s request, but when he learns a shocking truth about the groom, he tries to break up the marriage and earns a bad name.

Sathya (S. J. Suryaah) is a casanova by character and pursues Tina (Shradha Arya), a woman around. He sets his sights on Haritha (Nayanthara) and manages to woo her. She loves him whole heartedly and he is not in favor of that. At one moment he falls for Haritha, but at the same time, she comes to know about his real character, and she ends their relationship. The story is about how Sathya changes himself and earns her love back.

Varun Murali (Kalaiyarasan) is a well-known blind chef and the owner of a popular restaurant in Chennai. One night, Deepa (Sshivada) visits his restaurant asking for leftover food for homeless. Varun helps her and eventually falls in love with her daily visits. Meanwhile, Varun’s close relative, Sadhana alias ‘Sadhu’ (Janani Iyer) approaches his parents and reveals her intentions of marrying Varun, which they accept.
Varun decides to propose to Deepa in his restaurant, but he observes that she is in tears. She tells him that henchmen were pressing for their money and her father had promised to return the money in three days. Varun promises to help out from his own savings. On the same night, Varun is met with an accident and is hospitalized, during which his vision is restored. He is treated for three weeks and the hospital fee is paid out of his savings. Varun feels guilty and is disappointed for not helping out Deepa. When he is discharged, he is unable to locate her. When his family presses him to marry Sadhana, he agrees as he also likes her from his childhood days.

Mallamma, an orphan, loses her caretaker and her freedom to sing due to the jealousy of Dorasani, the village chief. However, her music teacher narrates the story of Rajanna to inspire her.

Inspector Ajit Rathod (Ajay Devgn) is on a mission to eliminate a notorious terrorist Azhar Khan (Rahul Dev) who killed his wife (Koena Mitra) and the latter is underground from the eyes of law and planning to destroy Mumbai. Now the story moves on to Amjad (Akshay Kumar), an auto rickshaw driver, who is searching his long lost brother Munna, and struggler Avinash (Tusshar Kapoor) who wants to be a star in Bollywood industry. Amjad wants to marry his lover Heena (Esha Deol). But her parents want her to marry a rich man. So Amjad plans to win her parents’ trust by a fake drama with Avinash and his friend to act as fake goons and they involve Rathod to arrest and win Heena’s heart. The plan goes wrong as real goons appear but Amjad fights them leading t Heena’s parents agreeing to marry her to Amjad. Avinash, who is a struggler, on the other hand, loses his job as an extra in films after an argument with an egoistic actor. A newcomer Indu (Laila Mehdin) is helped by Avinash to enter the industry and soon both fall in love with each other not knowing that she had been subjected to a compromise with the producer. Hopeless, Avinash decides to be an auto-rickshaw driver but Indu apologises and encourages Avinash to be a good actor. Soon, Avinash and Indu’s luck turns when the filmmaker (Asrani) casts them as leads in his next film after being impressed on their acting skills. Meghna, a news reporter (Lara Dutta) develops a liking towards Rathod, but the latter is still traumatised and angered on his wife’s death.

The film revolves around Kathavarayan (Karan), who sells illicit arrack in Hogenakkal. Though he is involved in arrack trade, he is a man with golden heart. Malathy (Vidisha), a student, comes to the village as part of her NSS project. She vows to end the arrack menace in the village and takes efforts to arrest Kathavarayan. Thanks to her efforts, Kathavarayan gets arrested and lodged in prison in Chennai.
Call it fate, Malathy is arrested for no fault of her in Chennai. Her efforts to expose drug-pedlers in Chennai backfires. They hatch a conspiracy and Malathy falls a prey to it. She gets arrested for possessing drugs and lands in prison.

Siva (R. Madhavan) is based out of Srirangam and he comes to Chennai to join a college. He stays with his sister (Anu Hasan) and her husband (Raghuvaran). Siva does not like his brother-in-law and never talks to him, despite several attempts made by his sister to convince both.
Siva meets Priya (Meera Jasmine) during a bus journey, and it is love at first sight for him. He again meets her on a few more occasions and proposes his love, but she warns him to stop following her despite liking him. Siva understands that Priya’s brother Bhaskar (Atul Kulkarni) is a local goon, and he attacks anyone who follows his sister.