Sethos is the nom de guerre of the shadowy "Master Criminal" in the Amelia Peabody series of historical mystery novels. Role in the novels He is first encountered in The Mummy Case, as the mastermind of an organized gang of thieves attempting to steal antiquities from Dahshoor, in which he is partially foiled by Amelia Peabody and her husband, Radcliffe Emerson. To their surprise, he reveals that he has spent most of the novel right under their noses, pretending to be a Coptic priest of the local village. Despite his disguise, Amelia feels sure he is English in origin. In Lion in the Valley, his nom de guerre is revealed, and he is thus described by an Englishman who hears of him during his brief foray into slum life: "He has no name, only a variety of appellations. Those in his employ, I believe, refer to him as the Master. To others, less intimately associated with him, he is known as Sethos... The men who work for the Master are the cream of the criminal crop. To be chosen by him is a mark of honor. Even those who are not in his employ are in deadly terror of him, and it is said that his revenge on a traitor is swift and horrible." (LITV, chapter 5) Amelia becomes obsessed with the idea of apprehending the Master Criminal and putting a stop to his activities. By the end of Lion in the Valley she is captured by Sethos, but astonished when he professes to be passionately in love with her. Amelia is starting to believe that she may be able to reform him when Emerson bursts in and fights with Sethos, who manages to escape. After realizing that he cannot have her, he promises never to harm or threaten her or her family. He reappears in the novels from time to time, often to rescue Amelia from other foes. Despite her occasional entreaties, he never gives up his illegal activities, which he takes considerable pride in. He is presumed dead at the end of The Snake, the Crocodile, and the Dog and again at the end of He Shall Thunder in the Sky, at which point it is revealed that he has been working for British Intelligence during the Great War. Family It is revealed in He Shall Thunder in the Sky that "Sethos" is actually Emerson and Walter's half-brother,