Jamal Malik ('Skins' star Dev Patel) is being beaten by Mumbai police for allegedly cheating on hit TV show 'Who Wants To Be A Millionaire?' One question away from the ultimate 20 million rupee prize, no one, including slick show host Prem (Anil Kapoor), believes a chai wallah (teaboy) like Jamal could know all the answers. As the tough inspector (Irfan Khan) replays Jamal's appearance on the show, it's revealed that each question corresponds to a specific life lesson from Jamal's tragic past.
Raised in abject poverty in Mumbai's grimmest slum along with older brother Salim, then orphaned by a Hindu mob attack, Jamal and Salim are forced to fend for themselves on the streets through opportunistic petty crime. They pick up a young girl, fellow orphan Latika (Freida Pinto), escape the clutches of a vicious Fagin-like crime boss, lose Latika, and continue their picaresque adventures, one step ahead of the law. As adolescents, however, Salim becomes entranced by a life of crime and Latika's unexpected return sets brother against brother. Will Jamal salvage his girl, his fortune and his life on 'Millionaire'?