Paapi Devataa tells us about Ram Kumar Singh who re-locates himself from Allahabad to Bombay by a train. During the this time, his wallet and clothes are stolen. And he registers a complaint to the railway police for his belongings that he was stolen during his journey. Meanwhile, a very kind-hearted Rahim Khan takes him home, provides him food, shelter, as well as a taxi-cab so that he can earn money while looking for a job. Eventually they become close friends.
While driving his taxi on his first day, Ram meets Reshma and both fall in love with each other. He then plans to search for a good job and move out to his own apartment. What Ram does not know is that Rahim works for an underworld Don, Ratan Seth, and has also killed a man named Niranjan Das. And what Rahim does not know is that Ram is the Deputy Commissioner of the Police who suspects Ram of killing Niranjan Das.