Don (Amitabh Bachchan) is the leader of an underworld gang until Police Officer DSilva (Iftekhar) tracks him down and in an attempt to catch him ends up killing him. But Dons death is only known to DSilva. So Officer DSilva tracks down a lookalike of Don named Vijay. Vijay impersonates Don to take down the rest of Dons gang while the DSP promises him that he will give a proper education to his wards who are actually the children of Jasjit (Pran).

Meanwhile, Jasjit comes out of prison after serving his jail term, only to find Officer DSilva having a red diary that would show Vijays true identity. Officer DSilva is killed by Malik who is introduced as the Interpol officer, but is in fact the real king of the underworld. Its now a race to retrieve the diary in which the DSP has documented the substitution of the real Don with the innocent Vijay. One famous dialogue of movie is "Don ko pakadna mushkil hi nahin namumkin hai" (it is not just difficult to catc... Read More >> Don, it is impossible)