"When Professor Gleason (Lucien Littlefield) is murdered at a remote mansion in the Mojave Desert, fellow guests Charlie Chan (Sidney Toler) and "Number Two Son" Jimmy (Sen Yung) search for the killer. The suspects include their host (Douglass Dumbrille) and his wife (Lenita Lane), a descendant of the notorious Borgias. Poking around the estate, the Chans find poisons, a torture chamber and other means of doing in the couple's unsuspecting guests."