For thousands of years the world has been protected from evil by gargoyle knights - part demon, mostly human warriors, armed with unnatural strength and the power to shapeshift into ferocious, nearly unstoppable beasts. Now, a new threat looms on the horizon. Abaddon's seal, the barrier separating the human world from the demon realms, will soon collapse.Abdiel St. Jude knows how to replace it, but to do so he will have to cross lines that he swore he never would. His sister, Eden, searches desperately for another way, but the one she finds is darker and even more dangerous than anything she could have expected.Amidst the storm of subterfuge, deception, dark alliances, and death, loyalties will be tested, bonds will be broken, and one painful truth becomes frighteningly clear - when Abaddon's seal breaks, Eden and Abdiel will not be fighting on the same side.