Yamla Pagla Deewana is a family drama of a man in search of his estranged family. Paramveer Singh Dhillon (Sunny), an upright and honest man working as a loan recovery agent in a bank stays with his mother, his Canadian wife (Mary) and two sons in Vancouver, Canada. Paramveer's mother is a typical Punjabi housewife, had decided to leave her husband Dharam Singh (Dharmender) because she was fed up with his deceptive ways. But one night Dharam Singh quietly took away the younger son and vanished. Paramveer decides to go to India to look for his Father and brother.

The Father-Son duo Dharam and Gajodhar (Bobby) are the biggest conmen in Banaras. Dharam is a stylish man and a charmer.Women of all ages adore him. He does not believe in love. Gajodhar is just like his father except for the fact that he is more rustic in appearance and gets nervous in the company of women! How this family comes together through a comedy of errors is what the film is about.