The Film is based on William Shakespeare's Macbeth and in this movie the backdrop is Mumbai underworld. Maqbool (Irfan Khan) is a right hand man of Jahangir Khan (alias Abba Ji) (Pankaj Kapoor), a powerful underworld don. Maqbool is grateful and feels a close connection and personal indebtedness to Abba Ji. The movie gains pace with two corrupt police-men (played by Om Puri and Naseeruddin Shah) perdicting that Maqbool would soon take over reins of Mumbai Underworld from Abba Ji. These two thus play a role akin to the three witches in the original play.

Nimmi (Tabu) is Abba Ji's mistress, but she secretly loves Maqbool. Maqbool loves Nimmi, too. Nimmi also encourages Maqbool's ambitions and persuades him to kill Abba Ji in order to take over as don. Maqbool is torn between his love for Nimmi and his loyalty to Abba Ji, but he begins to prepare the ground for becoming don by ensuring that others in the line of inheritance cannot interfere. Finally, in a dramatic scene, Maqbool murders Abba Ji in cold blood while he is bed at night, with Nimmi next to him. Maqbool gets away with it and takes over as don, just as planned; but both he and Nimmi are haunted by guilt, seeing Abbaji's ghosts and unable to wash the blood from their hands. There is also suspicion within the gang of Maqbool's role in the death of Abba Ji, and eventually the 2 lovers meet with tragic ends.
In addition to the portrayals of the three tragic heroes, the film offers performances by supporting cast members, in particular Om Puri and Naseeruddin Shah, who open the film in their roles as black comic relief corrupt police inspectors-cum-astrologers, who predict the fall of Abba Ji—who has them on his payroll—and the rise and fall of Maqbool. Contrary to the original play, the corrupt cops are not just passive soothsayers. In an effort to what they refer as "balancing forces," they also actively involve in shaping events, like aiding in providing information to Abba Ji's enforcers to wipe out a rival gang, using subtle nuances in coercing Maqbool to shift loyalties, deliberately botching an "encounter" attempt on Riyaz Boti (Macduff) and subsequently setting up an alliance between a rival politician (to the incumbent one, backed by Abba Ji) and a fleeing Guddu (Fleance) and Riyaz Boti against Maqbool.