The evil Dr. Mabuse develops a death ray with which he threatens the world.

"The Death Ray of Dr. Mabuse", tells the of when British Secret Service agent Major Anders investigates Professor Larsen, who has invented a death ray on his island. Included amongst the parties trying to obtain the death ray is the arch criminal Doctor Mabuse. Anders leads an army of frogmen to stop Larsen and Mabuse.—The Professor