When it's discovered that four prominent members of the community are crooks and black marketeers, young Akash (Rajesh Khanna) -- posing as an expatriate smuggler -- teams with his girlfriend, Chanda (Mumtaz), to expose them. But to nail the quartet -- a tradesman, a doctor and a builder, all led by a wealthy industrialist (Madan Puri) -- Akash must get them to confess their misdeeds while Chanda surreptitiously captures everything on film.

The philanthropists and pillars of society, a doctor, a builder, and a merchant, led by the rich Dharmalingam, are in fact villains dealing in crime and black market. The protagonist 'Durai' is set out on a quest to vanquish these enemies of the nation

In order to arrange for funds to save his dying mother, Mohan commits a petty theft. Soon, Mohan transforms into the criminal mastermind Mounto and is later hired by the CBI to work for the country.