Somewhere in the heart of Africa, a young archaeologist disappeared in the remote jungle mountains—Erich von Harben, son of an old missionary friend of Tarzan of the Apes. Now the ape-man seeks to rescue the lost scholar. The trail leads to a mysterious valley where Tarzan discovers two surviving outposts of ancient Rome, virtually unchanged by time. And there, Tarzan is thrust into the bloody gladiatorial arena, doomed to face every peril the cruel and corrupt emperor of Castra Sanguinarius can devise to ensure the ape-man’s death. Miles away in Castrum Mare, Erich von Harben also awaits execution upon the sands of another tyrant’s arena, destined to die before he can pledge his heart to the fair Favonia, daughter of one of the emperor’s favored patricians.