Chor Sipahee (1977)

Reformist Bombay Police Inspector Shankar Kumar would like to try a new approach to tackle crime - make new leaves of criminals by making them change their ways. He tries this on Raja Khanna alias Raja Dada, but in vain. When he comes to know his family, which consists of unmarried sister, Bharti, and an elderly and ailing mother, he decides that he must do something more to help Raja. Before he could think of anything, Raja is arrested for the murder of a police informer named Bichoo. Shankar destroys the evidence that links Raja to this murder, thus losing his job, facing criminal charges himself, and getting a jail sentence. When he comes out of jail, it is no longer the same Shankar - but one who is ready to join Raja as his criminal partner. But Raja is not the same petty criminal anymore - he has joined forces with international gangs of smugglers and may not quite be receptive to Shankar's request to join his gang. Shankar will now have to prove himself worthy of joining this gang - and for this he may have to sacrifice all virtues that he has learned to live with since his childhood.