After Usanga’s obsession with the airplane ends disastrously, Tarzan, Bertha, and the wounded Smith-Oldwick move deeper into unknown country, encountering a black lion, mysterious footprints, and a night attack before discovering Xuja, a strange walled city inhabited by a violent and mentally unstable people ruled by an equally dangerous royal family. When Bertha and Smith-Oldwick are taken captive and face death inside the city, Tarzan infiltrates Xuja, finds them, and leads a desperate escape through the city and surrounding gorge until the survivors finally reach British troops. In the closing revelation, Bertha Kircher is exposed not as a German spy but as British intelligence agent Patricia Canby, and a German officer’s diary proves that Jane was never killed, giving Tarzan renewed hope and turning his long campaign of vengeance into a determination to return and find his wife alive.
