The narrator, an elderly man, records an expedition to the high plateau of Mur and its ancient underground city, following the eccentric antiquary Ptolemy Higgs and companions. They uncover a mysterious ring linked to an ancient queen and are drawn into tribal conflicts, betrayals, and perilous journeys that include failed rescues, hunger, a palace burning, and confrontations with hostile forces and wild beasts. Personal stakes emerge when the narrator seeks a kidnapped son, leading to oaths, trials, narrow escapes, and hard choices that test loyalty and endurance before a final reckoning.