Siddhant Rai (Rishi Kapoor) is a successful architect and lives with his three kids Rohit, Rahul and Rani in a palatial bungalow with their pet dog Casper and family butler Banke Bjhari Chaturvedi and of course the villainish uncles Vikram, Prabhakar and brother-in-law. Siddhant arranges for a governess to look after them, as their mother is no longer alive. But the kids are so naughty that they drive away every governess or master hired by their father. Siddhant needs to go away for a project but before he leaves he arranges for a governess.
On the other hand Shekhar (Ajay Devgan) a small time thief robs a bank and he is evading police when he sees Anna (Kajol) who is on her way to Siddhant's house for her job of a governess. He falls in love with her instantly and even manages to convince Anna that he knows her and confesses his love. Anna is in a state of shock when Shekhar's friend Jaddu covers for him by telling her that she resembles his ex-girlfriend. Anna meets Siddhant and is introduced by him to his children.
There began a series of pranks. Kids scare Anna and she in turn with Siddhant plays the same trick on them. Shekhar on his front keeps confessing his love to Anna and proposes marriage to her. Kids play a crude prank on Anna by mailing her a telegram informing her parent's death. Anna is hurt by the prank as she is an orphan, the kids realize their mistake and accept her as an elder sister. Anna too confesses Shekhar about her love for him. And the kids and Siddhant decide to get her married to Shekhar. However Shekhar is arrested on the day of the marriage and Anna heartbroken leaves the house.
Siddhant and kids set to get her back but they meet with an accident in which Siddhant is killed. Now the Uncles claim for their share in the property when a strange character claiming to be Siddhant's brother comes in. He is actually Rajit Rai who left his house when he was eleven. He is none other than Shekhar and he wins back the confidence of Anna and the kids. In this way Shekhar, Anna, kids and the butler saves the fortune of Siddhant Rai from the greedy relatives with the help of a real yet unreal Raju Chacha.