This is a mystery story set in the South California desert. Charlie Chan, the Chinese detective from Honolulu, is entrusted with the safe delivery of a string of pearls to a millionaire's isolated desert ranch. Suspecting all is not well at the ranch, he disguises himself as a servant to investigate the mystery. Other characters include the jeweler's son who accompanies Charlie, a pretty location-finder connected with the movies, the millionaire's secretary, a jaded newspaperman and a mild-mannered naturalist.