Rakesh Trivedi (Abhishek Bachchan) comes from a small village. His father is a ticket collector on the train, and wants him to get into a similar occupation as well. However, Rakesh has big dreams; he is forever coming up with new business plans and is convinced he will make it big one day. He adamantly refuses any notion that he will one day work in a 9-to-5 environment.
Vimmi Saluja (Rani Mukerji) is the daughter of a Punjabi family in another small village; she spends her hours watching films and studying supermodels, and dreams of becoming Miss India one day.
One day Vimmi's parents tell her they have arranged her marriage to a young man with a decent job. At the same time Rakesh's father gives him an ultimatum ÃƒÂ¢Ã¢â€šÂ¬Ã¢â‚¬Å“ go to the interview for the job his father has arranged for him, or get out of the house.
Rakesh and Vimmi both pack their bags in their respective homes and sneak out in the dark of the night. They bump into each other at a train station, and become friends after realizing their stories are similar. Both support and encourage each other to achieve their dreams: Vimmi tries to enter herself in the Miss India contest but gets thrown out after an argument, and Rakesh tries to sell his ideas for an investment scheme, but a businessman turns him away. In fact, a man he had met at a restaurant stole ideas from Rakesh's presentation file and when he enters the office, the interviewer states someone before him came in with the same idea. After finding out that the businessman who Rakesh had approached has used his idea to make money for himself, he and Vimmi con him and take money they believe is rightly theirs.
Once they realize how easy it is to con people, they decide to run some more scams in order to raise money to make it to Bombay.
Unfortunately for India, they find the lifestyle too exciting to give up. Adopting the fake names of 'Bunty' and 'Babli', they successfully pull off scam after scam, looting and conning rich people dressed as local guides, religious priests, health inspectors, business partners, etc. Their flamboyant antics make them famous in newspapers nationwide. Soon their friendship leads to romance and they decide to continue scamming the rich as husband and wife.
Little do Rakesh and Vimmi know that ACP Dashrath Singh (Amitabh Bachchan) is catching up with their scams and pranks, getting closer each time. He relentlessly pursues them across India in the hopes of putting them behind bars. To complicate matters, Rakesh and Vimmi have a child, and after a very close call eluding Dashrath they decide to quit conning for their child's sake. Ironically, this decision leads to their capture by Dashrath. While in custody, their heartfelt confessions and conversation soften the detective's heart and he lets them go, certain he has destroyed Bunty and Babli's career as criminals.
Years later, Dashrath rescues them from their mundane and domestic lives to work for the nation thwarting the activities of other scammers.