War is being waged against the Descendants and Saira Elian is desperate to stop the Mongers' savage bid for power ...

Saira's search for kidnapped mixed-bloods draws her into the Mongers' stronghold, revealing the horrible truth behind the irresistible Monger ring and the vile plan to cleanse Family bloodlines ... permanently.

Under threat of a brutal massacre, Saira and Ringo travel back to Bletchley Park during World War II where they team up with Archer from the past to crack a Nazi code and expose a Monger intent on changing the course of history. They join forces with a female commando from the French resistance to hunt down an elite unit of Monger soldiers - Hitler's Werewolves - before the terror squad can strike a fatal blow at the heart of the Allied war effort.

Their manhunt drags Saira, Archer, and Ringo into the London Underground on the eve of a Nazi bombing raid where they come face-to-face with a Monger assassin on a suicide mission. With the lives of all mixed-bloods in peril, Saira must make a sacrifice that even Time may never forgive.