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.
Eduardo Ciannelli
as Doctor Satan
Robert Wilcox
as Bob Wayne / Copperhead
William Newell
as Speed Martin
C. Montague Shaw
as Prof. Thomas Scott
Ella Neal
as Lois Scott
Dorothy Herbert
as Alice Brent
Charles Trowbridge
as Gov. Bronson
Jack Mulhall
as Police Chief Rand
Edwin Stanley
as Col. Bevans
Walter McGrail
as Stoner
Joe McGuinn
as Gort
Bud Geary
as Hallett
