Thrilling, dangerous adventures confront Nancy Drew while on a safari in East Africa with a group of American college students. Excitement runs high as the teen-age detective delves into the theft of a fabulous sapphire formed by nature millions of years ago. The mystery starts in Nancy's home town. Her lawyer father's client, Floyd Ramsay, who fashions beautiful and unusual synthetic gems, is accused of stealing the magnificent spider sapphire and exhibiting it as his own creation. Mr. Ramsay's enemies blackmail him and by their vicious acts try to deter Nancy from going on the safari.

Readers will join Nancy as she uncovers a nefarious scheme and solves the strange disappearance of an injured jungle guide.