The film opens with a man (Aravind Akash) and woman interviewing civilians’ thoughts on love and the opposite sex. After a mixture of answers, they cease their questions and the credits roll. The credits end as a boy, after being rejected by his girlfriend, commits suicide by jumping in front of a passing car. Karthik (Vinay Rai) walks off, disturbed, to his girlfriend Jhansi’s (Sadha) office. There, he is criticized by her for his antics with other women and his lack of passion for their love. She walks off, ending their relationship.

Dhinakar (Jai Akash), hailing from a middle-class family, and Nancy (Madhumitha), a software engineer and sole breadwinner for her family, are neighbors who are in love with each other. However, their dreams of getting married are shattered when their self-centered parents decide on proposals of their own choice. Notwithstanding the overbearing parental pressures, Nancy marries Victor (Prakash Raj), a multimillionaire businessman, while Dhinakar marries his cousin – but not before the lead pair enters into a sly pact. Dhinakar and Nancy contrive to marry the spouses chosen by their parents, only to officially dissolve their unhappy unions later and thereby pave way to their union. After a sequence of events, Nancy successfully convinces Victor about her unreserved enthusiasm for her past love, gets her divorce, and takes the first step towards making a fresh start, but events overtake her in an unexpected final act.

The movie is all about a group of five college friends — Shaam (Shaam), Imaan (Arya), Pooja (Laila), Priya (Asin) and Irene (Pooja). The friends gather for Imaan’s wedding, years after everyone has parted ways.
The movie starts with Pooja leaving USA to go to Imaan’s wedding. Meanwhile, back in India, everyone else is helping Imaan with the preparations for his wedding and catching up with their long lost college friends. The movie goes through series of flashbacks of old memories during their college days. Imaan and Irene meet for the first time, after a long time. The first flashback occurs. They were once in love; however it didn’t turn as Imman had expected it to be.

Unemployed Shakthi Singh lives a poor lifestyle along with his widowed and ailing mother and a sister. His mother falls ill and gets admitted in hospital. While on his way to an interview with HSBC, Shakthi sees a beautiful girl, gets distracted and misses his bus – route No.12B. As a result he misses the interview, and ends up getting employed as a Garage Mechanic with Madan, his friend. He does meet with the same girl, gets to know her name is Jyotika, who lives a wealthy lifestyle with her mother, Sulo, while her dad is away on business. Both continue meeting not aware that her marriage has been arranged with Pratap. This story also depicts the possibility of Shakthi catching the 12B on time, attending the interview and getting hired, pursuing Jyotika in vain, and ending up in the arms of his co-worker, Priya. Both possibilities end up with Shakthi getting involved in a vehicle accident – and no guarantees that he will survive or wed Jyotika.