Hoppy and his pals arrive in a remote town to investigate the counterfeiting of both U.S. and Mexican money; his only clues are the name "Mordigan" and a drawing of a comet. He quickly finds out that Mordigan is the town "boss"; but what or who is "the comet", and why are Mordigan and his henchmen intent on persecuting a young woman, her drunken brother, and her deathly ill sister-in-law who've also just arrived in town?

Los Angeles, 1953. The author David L. "Dave" Brady wants to bring a missed ex-newspaperman back to Los Angeles. Therefore Dave has to travel to Mexico City. Dave gets involved with a murder case that occurred fifteen years ago. It's an obsession for Dave to solve that murder.

On his way to a post as special adviser of the new parachute troops of the French Foreign Legion in Morocco, Paul Dumont meets the beautiful Helene on the ship. A romance ensues, but the two decide to part when Paul learns that Helene is the fiancée of his best friend and fellow officer Raoul. Raoul is wounded during an Arab attack and the wedding is postponed, and Helene and Paul are thrown together and find it impossible to hide their feelings. The meet in the tent of Hassan, a fortune teller, not knowing the tent is a storage place for arms and ammunition belonging to Addullah, an Arab leader determined to avenge the death of his brother Ben Ali.