Boy Friend movie starts off with a cricket match between SMCE college and Banglore Engineering College. With 18 runs needed of the last 3 balls, in walks Ramesh Prasad (Manikuttan) and not surprisingly whacks 3 sixes to win the match for his college, much to the delight of his girlfriends and the Principal who is a Father (Lalu Alex). Ramesh has a lot of fans in college - predominantly female.
However Ramesh does not have time for any of them. His “girlfriend” is his mother . Ramesh’s father had commited suicide long ago and he is very close to his mother. Nandini Prasad (Lakshmi Gopalaswamy) who is Ramesh’s mother has filed a case against the Home Minister Natesan (Mukesh) for trying to molest her. MLA Thankappan (Harisree Ashokan) is his confidante. The court acquits Natesan.
Natesan comes to Ramesh’s college for an award function and in his speech does a character assassination of Nandini questioning her morality. Her son repsonds to the allegations by smacking Natesan with the very cricket bat he had awarded to Ramesh.
The same night, Natesan is murdered. Naturally everyone suspects Ramesh who goes hiding. Commissioner “Idiyan” Kartha (Sreenivasan) who is entrusted the case along with CI Vighneswar (Jagadish). Kartha - the cool and bumbling police officer despite being relieved from the case finally manages to find the real culprits.