The film deals with the ever going Hindu-Muslim problems and has a lovely love story threaded through it.
An American-born man (Abhishek Bachchan) brings his ailing grandmother (Waheeda Rahman) back to India. However, what he assumes will be a short trip turns into life changing journey for him.
In the ancient part of Delhi, Chandni Chowk, which represents chaos, different religious faiths and beliefs of the people, which has a pin code of 110006, and is affectionately called Delhi-6, he falls in love with the petite Bittu (Sonam Kapoor).
Amitabh Bachchan in a short role plays the part of Abhishek's grandfather, while Rishi Kapoor plays the role of a Muslim man who was once upon a time in love with Abhishek Bachchan's mother but lost out to his father (Gulshan Grover) who also happens to be his best friend. In spite of that, he treats Abhishek as his own son helps Abhishek with his problems.