In the year 2065, a scientist (Arya) invents a time machine. To prove its capability, he sends it back in time to 2015, programming it to return within forty seconds. However, the machine does not return.
The time machine is seen by three people in 2015 — Elango (Vishnu), a budding entrepreneur whose ideas are rejected by all and who is struggling to maintain his relationship with his rich girlfriend Anu (Miya), who is embarrassed at the fact that Elango is unemployed; Elango’s best friend Pulivetti Arumugam (Karunakaran), a fake astrologer; and an inventor Giridhara Parthasarathy (T. M. Karthik), who makes a living by repairing home appliances. The three of them are involved in an accident and witness the time machine while recovering from the shock. While Parthasarathy decides to keep the time machine for himself, he suffers an electric shock and ends up in a coma, prompting Elango and Arumugam come to steal the time machine from Parthasarathy’s shop. The duo use the time machine to make Arumugam’s astrology practice extremely successful by going back in time and finding things lost by people under the guise of astrology. Elango further uses the machine to impress Anu’s industrialist father Rajarathinam (Jayaprakash) by going to the future, obtaining the stock market results and successfully “predicting” them in front of Rajarathinam and his company’s board of directors. Rajarathinam soon approves the marriage of Anu with Elango.

A woman, who lives in a village where female infanticide is a common practice, goes to great lengths to get justice when her sister and her newborn child are murdered in cold blood.

Azhagu who stay in small hut, born and brought up in jungle. he spends his life with animals. After initial differences, he gets accustomed to Selvi and falls in love with her. Both decide to get married.

The film takes us through a journey where one faces the consequence when two people meet each other. Devathai, who is the daughter of the ex minister Chitravel comes across her first love Kaushik. Meanwhile her elder sister Nithya develops a relationship with her fathers rival Paddi Alandhans son Prakash. A special investigating officer Nagaraj is set to unravel the clues and through his investigation, he gradually realizes that it is not a man, but demonic forces leading to gruesome murders.

Based on true incidents, a south Indian Hindu man falls in love with a Muslim woman–taboo in the small village from which they hail. They marry against family wishes and move to Mumbai, where he works as a reporter for a large daily newspaper. Eventually, the couple has twin boys. The rest of the film is set during the December 1992-January 1993 period when the Ram Janmabhoomi-Babri Masjid controversy raised religious tension in Mumbai and other parts of India, which sparked rioting and violence. The couple is separated from their children, and the fathers of both parents are killed when their home is burned by rioters. A reporter is shown interviewing politicians from both factions as well as the police. An underlying moral of thinking of oneself as an Indian rather than a Hindu or a Muslim is prevalent throughout the latter part of the film. The family is finally reunited after much searching through hospitals, morgues, and shelters.

Shanmugam (Parthiban), a veterinary doctor, lives in the city with his wife Valarmati (Devayani) and their two children. In school, Shanmugam was in love with his classmate Dhanalakshmi (Nandita Das), but fate had forced them to go their separate ways, with Dhanam being forced to wed her brother-in-law (Sayaji Shinde). One day, Shanmugam spots Dhanam, who, having lost her husband, now lives a life of poverty on the platforms with her son Balu. After an unsuccessful attempt to find her a job in a friend’s house, he hires her as their servant-maid. However, memories of the past start to create a tension between Shanmugam and Dhanam, despite their attempts to maintain a distance.
One day, Valarmati finds out from Shanmugam’s old classmates how they both were in love when they were young, and she starts fearing that Shanmugam will leave her and her children for Dhanam. Valarmati becomes so distraught that she even humiliates Dhanam at a party organized by one of their friends. When they return home, Valarmati confronts Shanmugam, and an argument ensues. Dhanam overhears their argument and silently goes to bed. The next morning, Dhanam and Balu are nowhere to be found. When Shanmugam searches the house, he finds a letter written by Dhanam saying that she wants Valarmati and Shanmugam to be happy and that she doesn’t want to come between them. Soon, Valarmati realizes the truth and wants to bring Dhanam back home and ask her for her forgiveness.

The underworld don Billa (Ajith Kumar), featured on Interpol’s criminal list, is hiding and operating out of Malaysia. DSP Jayaprakash (Prabhu) has spent the last few years looking for Billa, leaving behind a life in India.
During a chase with the police, Billa is severely wounded after an accident and dies in front of the DSP. The DSP then secretly holds a burial of Billa. Interpol officer Gokulnath (Rahman) is assigned to work with DSP Jayaprakash to capture elusive Billa as no-one knows of Billa’s death. DSP Jayaprakash keeps the death of Billa as a secret even from his fellow officers, and tracks down a look-alike called Saravana Velu (Ajith Kumar), a lowly pick-pocket. He asks Velu to infiltrate Billa’s gang by pretending to be Billa. In return he will make sure that the child Velu adopted, Karan, gets a proper education.

Achyut and Anand are brothers, Jyosthna is a tenant in their home. Both the brothers try impressing her.

Things take a dark turn as Mali plots to murder his girlfriend who breaks his heart with the help Aravind.

Vishu and Ramu are a pair of Indian twins living in America with their father, Rajamani. When Madhumita (Aishwarya Rai) and her brother come to America to get medical treatment for their ailing grandmother, Vishu and Ramu end up meeting them at the airport. Vishu falls in love with Madhumita, and the couple has everyone’s blessing, except for Rajamani, who is estranged from his own twin brother. He only wants his sons to marry twin sisters, so Madhumita pretends to have a twin in order to please him. As Madhumita puts on a charade by creating Vaishnavi, all goes well, until Ramu falls in love with Vaishnavi. Now the truth must come out, before Madhumita has to marry both of Rajamani’s twin sons.

Kathirvel Murugan (Bharath) is a software engineer in Chennai. He shares his room with friend Sakkarai (Santhanam). Kathir hails from Usilampatti but wants to project him as city-bred and his ambition is to settle in USA. Kathir’s father Sevaka Pandian (Sampath Raj) is against his son’s attitude. An influential local chieftain, he is against inter-caste marriage and love. Kathir meets Nisha (Rima Kallingal), who too wants to go abroad. Nisha loses her passport, and Kathir helps her find it. Slowly, he falls for her. Meanwhile, Sevaka Pandian arranges for his son’s wedding with a High Court judge’s daughter Thangameena (Anuja Iyer). In the meantime, Kathir and Nisha get their visa and get ready to leave together for USA.
Kathir thinks that he has escaped from his marriage, and when he wants to propose to Nisha, he gets a rude shock. She informs him that she is going to USA for her marriage. In the meantime, Sevaka Pandian comes to know about their relationship and kidnaps her. Afterwards Kathir also comes to know about it and saves Nisha, but her marriage gets stopped. After 10 months, they both meet in the same country again. Kathir doesn’t want to see her, but his mind changes, and he tries to make Nisha love him. At last, they both fall in love with each other. Now they return to their hometown for their marriage. Initially, Sevaka Pandian doesn’t allow. Later Kathir convinces them and they both marry each other making it a very happy ending.

Just as everything was falling into place for, a man is distraught when the girl he loves dies in a blast. Fate plays yet another trick on him when he finds himself face to face with her lookalike.

When stuntman Sambandham (Kamal Haasan) and Dr. Janaki (Simran) come across each other at his brother Anand’s (Abbas) and her best friend Malathi’s (Sneha) hastily planned wedding ceremony, they instantly develop a dislike for each other. They both have a very low opinion of the opposite sex, and staunchly believe marriage is not the way to go for the two newly-weds, whom they try to discourage from proceeding further.
Janaki convinces Malathi to test out her theory that men are after only one thing, by forcing Malathi to delay their consummation for three months. She is sure Anand will not be able to do so and this will prove to Malathi that Anand is just another low-class male, like all others.

Rajesh goes to jail for killing his second wife. Meanwhile, his son grows up among the local goons and establishes himself as a full-fledged rowdy. Rajesh wants him to get married but he hates women.

On a business trip to Switzerland, Vijay meets Meenu and decides to get married to her. Meenu’s brother Nagaraj asks Vijay to leave India and get settled in Switzerland with his family.