3 Idiots is a movie about three engineering students who are studying at Imperial College of Engineering. Rancho, Farhan and Raju are close friends who reside together while trying to finish their engineering degree. Farhan is passionate in becoming a wildlife photographer yet studies to be an engineer to follow his father's wishes. Raju is pursuing engineering in hopes of uplifting his family from poverty. Rancho studies engineering for the simple fact that machines are his passion.
Rancho has deep philosophical belief that one must follow excellence over success. For once excellence is achieved, success will follow no matter what.
However, Professor Viru, also known as Virus, does not agree with Rancho's philosophy. The dean's favorite student is named Chatur "The Silencer" also favors the deans approach, and that is mindless memorization to attain his goals of having a high corporate status.
The love story angle of the movie is between Rancho and Pia. Pia is the dean's daughter and a medical student.
Since the dean has grown distasteful with Raju and his friends, he schemed to have a nearly impossible final exam. Pia has learned about the dean's plan, and relays the information to Rancho. Not wanting their friend to fail the exam, Rancho and Farhan breaks into the dean's office with the plans of stealing a copy of the final exam. Unfortunately, they got caught by the dean and were expelled instantly. Pia was not happy about her father's actions and confronts him with true reason of his brother's suicide.
The story continues to juggle between flashbacks of the past and the present. However, the main reason that they were back together because Chatur is calling out Rancho to prove that his philosophies on learning are superior thus wants to show Rancho about his corporate success.
They were looking all around to find Rancho until their quest led them to an estate in Shimla. They believe that Rancho is residing in the estate. They asked for an audience with Rancho. However, they met a totally different person. Surprisingly, that man was truly Rancho, and the Rancho they knew was a totally different person.
So the quest to find the real Rancho continues until they end up in a small village. At this time Chatur was growing displeased since he has a very important business deal to seal with a world renowned scientist named Phunsukh Wangdu.
They finally met Rancho in the village, and all of them were ecstatic. However, Chatu mocked Rancho about his career until he found out that the real name of Rancho was Phunsukh Wangduh, the very scientist that he is trying to close the deal with. Chatu admits defeat in the end.