Miss Mary Morstan contacts Sherlock Holmes for his help regarding her father, captain Morstan, who disappeared 10 years ago. Since his disappearance she annually receives a valuable pearl by post from an unknown person. The mystery leads Holmes and doctor Watson into an intricate plot regarding a lost treasure belonging to four convicts on the Andaman Islands。故事的背景是公元前二百万年,恐龙的石器时代,某个小镇住着一群石器时代的原始人,但他们的意识却非常现代。聪明的弗雷德用石头、动物骨骼和毛皮制作出电话机、照像机甚至影印机。家庭厨房设备还有以猪提供动力的环保型垃圾处理装置。。