With Earth on the brink of war with Ada's homeworld, the Alliance has reached crisis point. While Ada faces the truths her guardian, Nell, kept from her all her life, Kay faces the backlash from his father’s last, terrible act as a council member. Nobody can be trusted, and betrayal lurks at every corner.

As the inevitable cross-world war threatens everything they care about, Ada and Kay must make devastating choices. If the Alliance falls, so will the Multiverse. And this time, there’s no going back…

This blend of contemporary fantasy, murder mystery, and an action-packed world-hopping adventure will appeal to fans of the alternate Londons of Ben Aaranovitch and VE Schwab, the modern magic of the Dresden Files, and the genre-blending of Genevieve Cogman’s Invisible Library series and Diana Wynne Jones’s adult novels.