Employed as an Air Hostess with Spice Jet, Mumbai-based Preeti Sengupta has a boyfriend in Karan Malhotra. Both decide to rent an apartment near Oshiwara and share the rent. But when she notices that he is paying more attention to other females, she breaks up with him, and decides to rent a room to a female paying guest. She does find one in Neha Bhargav, an employee from a book store, who calls her 'Didi', agrees to pay the rent on time, and even does all the housework and cooking. Preeti does make up with Karan at the intervention of her neighbor, Madhusudan, but feels threatened by Neha, who is getting overly friendly with Karan. After Madhusudan's cat dies unexpectedly he decides to probe further into Neha's past - and it is this decision that will change everyone's lives forever.