Jem Carstairs and Tessa Gray are finally united after waiting over a century to be together, but they become aware a dark threat is looming over a child of the Shadow Market: a lost Herondale, from a line of Herondales who have used the Market to hide from their fellow Nephilim. Now is the time for the lost Herondale to be discovered. Jem and Tessa have to find him before his enemies can.
It is only three years since Tessa Gray lost her beloved husband William Herondale, and she is searching for a reason to live, trying to find the path of being a warlock with the guidance of her friend Catarina Loss. World War 2 rains down destruction on their world, and Tessa and Catarina become nurses who make bargains at the Shadow Market for enchantments to help suffering mundanes. But can Brother Zachariah bear to see the woman he loves risk...