Mumbai Underworld tells the tale of two 12 year old boys (Vijay and Yakub) who grow up in the slums of India. Wanting to make a name for themselves in the mafia world, they start delivering drugs and loot people with the help of their transvestite friend. Things go wrong when they are sent to a juvenile reformatory after being wrongly convicted for a murder. They learn life is much tougher in the reformatory than the world they came from. They are tortured by the warden and senior inmates. But ...