Jai (Amitabh Bachchan) is an expert gambler, has been for as long as he can remember, and has never lost a game. These skills bring him to the attention of the underworld don Saxena (Utpal Dutt), who is interested in hiring him to win large amounts of money from rich people and then influencing them into doing whatever he wants. Jai agrees to do so, and plays successfully, though unknowingly to entrap Nath (Jagdish Raj) who works for the government. After losing large amounts of money, he is blackmailed into revealing the blueprints of a top-secret military laser weapon that can hit any target within 50 miles. When the Indian police come to know of this, they assign the case to Inspector Vijay (also Amitabh Bachchan), who is asked to apprehend Jai at any cost. The only problem is that Inspector Vijay is Jai's look-alike, and is not at all a good gambler.
After this Jai and Vijay get confusingly mixed up as Jai and Vijay both coincidentally are sent to Rome where Vijay is sent to retrieve evidence against underworld don Saxena by his former henchman and Jai is onto a money-making scheme where he would marry his rich girlfriend Mala (Neetu Singh) to inherit her money. Mala however mistakens Vijay for Jai at the Rome airport and Vijay decides to go along with this to find out who his lookalike is. Jai meanwhile meets Shabnam (Zeenat Aman), a club dancer who has been sent by Saxena to distract Vijay and stop him on his mission to retrieve evidence against Saxena. However Shabnam mistakens Jai for Vijay and Jai is embroiled into killing Saxena's former henchman to retrieve the blueprints of the laser weapon.