Based in a small town in the Northern part of India, Sahib Biwi Aur Gangster is a story packed with intrigue betrayal and ambition between a beautiful Begum, her Nawab husband and an ambitious young boy.
The Nawab and his Begum, live in their ancestral royal house trying to maintain the status and structure their ancestors had left behind. But due to the changing time, some extreme financial conditions and the long gone habit of a royal having a mistress, the Nawab tries real hard to maintain his status and financial conditions.
His rival political party, belonging to Gainda Singh is on a constant mission to eliminate the Nawab and his allies, to get a hold of the administration, which has been with this royal family for decades. Eventually leaving him with just one Kanahiya who is Saheb's most trusted and dangerous servant.
Due to the Nawab's interest in his beautiful mistress, Begum suffers seriously from the lack of his attention and tries to put every bit of her effort into getting him to come back to her or even spend a moment of his time with her. The Nawab starts taking contract killing assignments to be able to cope up with his lifestyle and to be able to get a stronger hold over his political situation while campaigning for the elections, which becomes a difficult battle considering the loss of his allies and deteriorating financial situation.
The drama in the plot walks in when the same rival gang plant Babloo, to get information and plot the Nawab's killing, as the temporary driver for Begum as her age-old driver meets with an accident, which was also conspired by the same group.
Begum suffering from the lack of her husband's attention and slightly hysterical due to the same gets into a sort of sexual relationship with this young driver who seems to be giving more of his time to her.
In this process, Babblo falls deeply in love with the Begum and lands up confessing of his connections and intentions in front of the Nawab. This is exactly the point where the entire drama between the Sahib, his Biwi and Babloo the gangster begins.
The story is filled with twists and turns as Biwi uses Babblo to get the mistress killed to gain back the lost attention from her husband. Babloo manages to fulfill her demand but in turn gets ambitious and wants the begum for him and the power which Saheb now holds after he eliminates Gainda Singh.