Spy Smasher Returns is a 100-minute abridgement of Republic's 12-chapter serial Spy Smasher. The original 1942 chapter play was based on the comic book character created in 1940 by C.C. Beck, Pete Costanza and Bill Parker. As in the comics, Spy Smasher's alter ego is playboy Alan Armstrong, here played by Kane Richmond. For the purposes of the serial's labyrinthine plotline, Alan is given a twin brother named Jack, who is killed off halfway through the action (thus providing a misleading chapter climax). Spy Smasher's assignment is to ascertain the identity of The Mask, the mysterious head of a Nazi spy ring operating in America. The Mask has in his possession a death ray and a "bat plane", both props borrowed from earlier Republic serials.