Prem Kumar (Vijay Sethupathi) is all set to get married to his lover Dhanalakshmi (Gayathrie Shankar). Two days before his wedding, Prem decides to try his hand at playing cricket with his friends Bagavathi alias Bugs (Bagavathi Perumal), Balaji Tharaneetharan alias Bhaji (Rajkumar) and Saras (Vigneshwaran Palanisamy). The game gets a little serious as Prem, in a bid to catch a ball, falls down, only to get injured in his head. He quickly gets back on his toes as the injury is not serious. Soon after the match, the friends are in for a shock. Due to the injury, Prem develops retrograde amnesia and short-term memory loss, wherein he remembers the chain of events which leads to the injury but forgets the last one year of his life and fails to remember everything after the injury. He remembers his life until college and recognizes his friends but is clueless about his upcoming wedding and about Dhana herself, as it is during the last one year that he met her, fell in love with her, and decided to marry her. Fearing trouble, his friends take him to a doctor, who says that he could recover anytime. Hence, his friends plan to keep him in their company, enact a drama until he ties the wedding knot, with the hope that he would get back his memory soon, while covering Prem’s disorder from everyone else. In the end, everything works out well, and Prem gets his memory back.

The movie begins at present day with Saket Ram (Kamal Haasan), an 89-year-old Hindu man at his death bed in Madras. He is being taken care of by his grandson Saket Ram Junior, a famous novelist who writes historical fiction, and their family doctor, Munawar. Ram Jr. explains how he grew up listening to his grandfather’s stories. He then narrates one of his grandfather’s strangest stories that he plans to use for his next novel. As Ram Jr. narrates the story, Ram is reminded of it.
The scene reverts to the 1940s, when he and his good friend, Amjad Ali Khan (Shah Rukh Khan) are archaeologists working together under their boss, Mortimer Wheeler, in Mohenjo-daro in the Sindh province in what was then North-West India. Relations are pleasant between the Indians and the English. Saket and Amjad do not approve of partition and the creation of Pakistan.

Easwaran (Arjun Sarja) is an upright, honest youth who runs a local cable channel in Kumbakonam. He is known to fight for causes of the society and the common man. He enters into fisticuffs with local MLA Poongundran (Sai Kumar) after he exposes his corrupt and greedy ways through his cable TV channel. Fearing trouble, his mother takes him to a saint in Thiruvannamalai. The Swami resembles Easwaran. A sequence of events forces them to swap places. The soft-spoken Swami tries to sort all issues through non-violent means (Gandhian philosophy). Halfway through, Duraisingam (Karunas) dies in the hands of Poongundran and his henchman (Vidharth). In the climax, Easwaran kills Poongundran.

Ayyanar, a barbarian, beats up innocents and rapes women. He gets married to Alagamma, a pretty girl, who hates him initially, but later decides to transform him. But his sinful past soon catches up.

Menon, a retired police officer, becomes a victim of political rivalry when he admits to have killed a boy and is imprisoned. His daughters take it upon themselves to prove their father’s innocence.

Two sons of a labour leader, who is framed by his employers, grow up amidst great difficulties. The elder son turns into a don while the younger, protected by his brother and mother, becomes a cop.

“Blade” Ganesh (Jiiva) is a henchman for a local villain Naaga (Sharath Lohitashwa) and is loyal to him. Vithya (Nayanthara) is the daughter of a local factory owner (Joe Malloori). She falls for Ganesh after he saves her from a kidnapping. Vithya’s father arranges for her to marry another man, but everyone learns about the love affair between Vithya and Ganesh, which creates animosity between Naaga and Vithya’s father. Blade gets caught between supporting Vithya’s father and standing up to Naaga. Blade saves the day by killing Naaga.

Kondapolam tells the story of Nallamala forest-based shepherds who are responsible for protecting their sheep from the dangerous attacks of the predators and the red sanders of the region.

A man, who lost his Muslim friend as he was in a relationship with a Brahmin woman, is hesitant about love. However, a woman falls for him and tries to help him overcome his past.

Raja (Nakul) is a kick boxer, a happy-go-lucky guy who falls madly in love with Valli (Chandni) who is a law student. She is into a lot of social causes and assists Kamaraj (Manivannan) who is fighting a losing battle against a thug Isaikimuthu. Valli along with her senior (Kasturi) tries to re-open Kamaraj’s suicide case and has evidence to prove that it was a murder, she is on the run. No, our macho hero turns her savior and tried hard to protect her. There is Reema (Avani Modi) and Wahab, friends of Raja who helps him. How Raja fights all the goons single-handedly and triumphs forms the story.

The film opens with a funeral partaking in an apartment where the police are involved saying he doesn’t understand the motive of the murder of Ram. His wife Janani hallucinates about her husband running away. She recalls memories and it continues with a flashback when Ram and Janani were 12th-grade students.
While she was from a middle-class family and Ram at that time lived with his father who was a businessman and his mother. After he saw Janani he helps fix her bicycle (it was raining heavily) but at the same time has a crush on her. He tells his friends Kumaran and Senthil about it they were from different schools but same tuition. One night he and Senthil stalked Janani and was caught by her father as he questioned them both. He slapped Ram and scolded Senthil for lying and warned them. Nevertheless, Ram visits Janani before he could ask she reciprocates his love. Janani’s sister Sumi makes sure her parents aren’t aware their secret love. The story returns to reality while Janani has a teary conversation with her mother about Ram. Soon she slept having a dream about when her family has a visa to go to the US and she had to go. When Ram heard this he decided that she could leave him. Instead of leaving him she appeared near him. He said she burned her passport and her mother disowned with a slap. She then urged Ram to marry her because of their five-year relationship. So he told his mother then urged his father who did agree and gave them a flat.After their marriage, Ram persuaded that her family to come and see her for she felt uncomfortable.He made a promise to not hurt her or allow anyone to. Ram and Janani were pleased with their life and were happy together.

Annakodi is in love with a boy who belongs to a different caste. When her parents learn about it, they disapprove of her relationship and force her to get married to someone else.