The Spark Man [Omar Kavak]; John (party guest); Val Hall; Harry (party guest); District Attorney Dillon (party guest); Alice Mason (special government agent, party guest); phony Spark Man [Duval] (villain, jewel thief); Dr. Dryden (villain, party guest)
Val Hall throws one of his famed costume parties, which is suddenly interrupted by a person in a Spark Man costume who is demanding guest's jewelry and wallets. However, the real Spark Man shows up and flattens the phony, only to be confronted by D. A. Dillon, keen on capturing the hero, but fails. Soon, one of the guests, Dr. Dryden, offers to drive Miss Mason home, but instead kidnaps her, and takes her to his cemetery arsenal hideout, closely followed by Spark Man. Dryden's intent in kidnapping Mason and others is to form a large Fifth Column army, but Spark Man stops that.