Simon learns the worst crime a Shadowhunter can commit: desertion of their comrades. In the early nineteenth century, Tobias Herondale abandoned his fellow Shadowhunters in the heat of battle and left them to die. His life was forfeit, but Tobias never returned, and the Clave claimed his wife’s life in exchange for Tobias’s. Simon and his fellow students are shocked to learn of this brutality, especially when it is revealed the woman was pregnant. But what if the child survived... could there be a lost Herondale line out in the world today?