Rajan Mathus (Anil Kapoor) lives in Chandni Chowk with his activist wife, Roma Mathur (Shefali Shah). By profession, he is a professor in Urdu Literature in Dr. Zakir Hussain’s College. He comes across a young boy named Numair Qazi (Anurag Sinha) who introduces himself as a victim of communal riots in Gujarat. In reality, Numair is a suicide bomber commissioned by a Muslim fundamentalist group to detonate a bomb near Red Fort on 15th August. Since he is on an important mission, Numair manages to take shelter in the professor’s house and succeeds in winning the couple’s trust and fondness. During his fifteen day roller coaster journey, Professor Mathur introduces him to the warm and loving people of his neighborhood who enjoy music, events and colourful festivals in perfect harmony together. On the other hand, the Professor also tries to make arrangements for Numair to get an employment entry pass for the 15th August celebrations at Red Fort.
However, Numair is astonished with some of the characters he meets in Chandi Chowk and perplexed on seeing their unity. Some of these are Shagufta, a modern Muslim college girl, the Professor's sharp-tongued wife Roma, Rahat, a Sufi pop singer, Miya an 84-year-old who is full of patriotism and the fun loving Sardar Kirtan Singh. But Numair also feels that he must keep his mind focused on his mission as he struggles to carry out orders from his superiors.
Amidst all the tension, he is caught in an emotional dilemma whether or not to go ahead with his mission. Despite his deep-rooted fundamentalist beliefs, he sees this as one of the most colorful and loving areas. There is no black and white here! Nevertheless he still decides to go ahead with his mission…. What is disturbing the mind of this young lad who has come here to attack? Doesn't the sacrifice of the Professor and his wife mean anything to him?