Bobo (Emraan Hashmi) is India's top magician, a star. But unknown to even his beautiful girlfriend Tamara (Huma Qureshi), his life is falling apart. Hallucinations about his dead little sister Misha are casting a dark shadow on his life, threatening his very sanity. He is left with no option but to seek psychiatric help in the form of the rather odd Dr. Palit who puts him under regression hypnosis to go back to the distant past, when Bobo was 11 and Isha 6.

A terrifying childhood story surfaces in which a dark supernatural power, in the form of a daayan (Witch) enters their life. A woman named Diana (Konkona Sen Sharma) moves in the building after Bobo goes to hell using the elevator, which causes her to surface. She charms Bobo's single father and agrees to babysit the kids. She soon becomes a part of the family by marrying Bobo's father, although the paranoid Bobo still believes she's a witch.