In Mitternacht, Switzerland to say hello to Lt. Frederic Ralston, the son of a client, Perry Mason also gets to meet the young woman that Fred has fallen in love with, Greta Koning. When they go to Fred's room to see him, they find the dead body of Capt. Joe Farrell and Fred standing there with a gun in his hand. Farrell and Fred did not get along and, while Farrell had been killed with Fred's gun, he says had just picked it up from the floor. Working with local police, Inspector Hurt, Perry learns from the military that Joe Ferrell was onto a scam having to do with a Nazi treasure at the bottom of the nearby lake. They believe that the eminent Dr. Kleinman is behind it all, but when they find him at the bottom of the lake, it's apparent they have two murders to solve. The victims of scam include an American, Frank Appleton, as well as an Argentinian, Juan Carlos Ramirez. Perry has an idea who is responsible.
—garykmcd