Le Mysterieux Docteur Satan

The wife of a psychoanalyst falls prey to a devious quack hypnotist when he discovers she is an habitual shoplifter. Then one of his previous patients now being treated by the real doctor is found murdered, with her still at the scene, and suspicion points only one way.

A mad scientist named Dr. Satan plots to steal key pieces of technology to enable him to build an army of robots based on his prototype to conquer America. The only one standing in his way is Bob Wayne, who fights Satan as the enigmatic Copperhead. Mysterious Doctor Satan is a 1940 film serial named after its chief villain. Doctor Satan's main opponent is the masked mystery man, "The Copperhead", whose secret identity is Bob Wayne, a man searching for justice and revenge on Satan for the death of his step-father. The serial charts the conflict between the two as Bob Wayne pursues Doctor Satan, while the latter completes his plans for world domination.

A wealthy society doctor decides to research the medical aspects of criminal behaviour by becoming one himself. He joins a gang of thieves and proceeds to wrest leadership of the gang away from it's extremely resentful leader.