Jupiter Jones, Pete Crenshaw, and Bob Andrews are helping Konrad deliver purchases made at the Jones's Salvage Yard to a millionaire distrustful of the world and his wife, a woman insistent that extraterrestrials will rescue them before the end of the world. After delivering their purchases, The Three Investigators are trapped on the millionaire's ranch by a road closure guarded by soldiers who don't seem all that military. When the cliffside blazes in blue flame and a flying saucer flies away, Jupe, Pete, and Bob are entangled in a mystery. Have extraterrestrials really come to rescue the millionaire and his wife or is this an elaborate hoax? Is there a traitor among the ranch hands? Find out in The Mystery of the Blazing Cliffs!