The walls of Ninurta keep its citizens safe. Kai always believed the only danger to the city came from within. Now, with a rebel force threatening the fragile government, the walls have become more of a prison than ever. To make matters worse, as Avan explores his new identity as an Infinite, Kai struggles to remind him what it means to be human. And she fears her brother, Reev, is involved with the rebels. With the two people she cares about most on opposite sides of a brewing war, Kai will do whatever it takes to bring peace. But she's lost her power to manipulate the threads of time, and she learns that a civil war might be the beginning of something far worse that will crumble not only Ninurta's walls but also the entire city. In this thrilling sequel to Gates of Thread and Stone, Kai must decide how much of her humanity she's willing to lose to protect the only family she's ever known.