Aiden Lobo is a graduate student in a world where magic, gods, and demons are part of everyday life. After a terrible betrayal, he is cursed with a Crack in his heart, slowly turning him into a living doorway for an ancient war demon. If Aeshma breaks through to Earth, he will kill millions.

But before Aeshma can open the Crack, Aiden is rescued by his guardian angel, who uses his own Light to seal Aiden's heart. As a servant of the divine, the nameless angel was supposed to kill Aiden to avert the growing cataclysm inside him. But he loves Aiden too much to end his life, even to save the world.

It's impossible for Aiden not to love his warm, generous guardian in return. He names the angel Eskandar, but then learns to his horror that because Eskandar was created for him, when Aiden dies, Eskandar will too. The angel has long since accepted this fate, but Aiden refuses to. He will do anything to keep his beloved angel safe. But with no other recourse than to sacrifice himself to prevent the apocalypse, there's only one way for Aiden to save Eskandar: a terrible betrayal of his own.