The movie is said to be inspired by the story of the notorious gangster of Mumbai Sheikh Dawood Ibrahim Kaskar, his growth from a small time smuggler to a gangster.

The role of Dawood is played by Emraan Hashmi and Ajay Devgan plays Haji Mastan the don who ruled Mumbai and its docks before Dawood became a threat.

Produced by Balaji Motion Pictures and helmed by Milan Luthria's `Once Upon A Time In Mumbai' traces the changing face of the Mumbai underworld and how it all started.

The film, set primarily in 1970s Mumbai, follows the rise of Sultan (Ajay Devgn), and the conflict, when Shoaib (Emraan Hashmi), challenges his supremacy, and usurps power to rule the murky underbelly of Mumbai.

The film is presented in a retro chic style and is a glamorous and powerful rewind to the golden era.

Kangna Ranaut and Prachi Desai add glamour to this all man story and the music is given by Pritam.