The entrepreneur and the actress fall in love, though she does not know that he is an entrepreneur. The film's story revolves around a rich business entrepreneur falling in love with an ad film actress. So, with the help of Chitra, Sanjay sets out on a revenge spree, searching for the murderer of the one love of his life. When her activist work for children comes in the way of child racketeers, she is killed by Lakshman when she intervened with his plan of kidnapping 25 young girls to Calcutta.
Chitra comes to know about Sanjay's love with Kalpana (Asin Thottumkal) a model cum activist. His story has also piqued the interest of a medical college student, Chitra (Jiah Khan) who is searching for a patient with an "interesting" record for her college project. His story in unraveled by a police officer (Riyaz Khan) who is hunting him due to several murders he has committed while trying to find his girlfriend's murderer through his diary.
He can now only live a comprehendible life by tattooing notes on himself and taking pictures of things with a Polaroid camera to remind himself of the incidents that have happened. Because of the severe injury on his head, his memory can only last for fifteen minutes and he doesn't remember events or incidents that have happened before in his life. Sanjay Singhania (Aamir Khan) is a rich tycoon suffering from short term memory loss due to being hit by a metal pole when trying to intervene on his girlfriend's murder.