Eight years ago, Luke Retter witnessed the brutal murder of his mother and sister at the hands of his demon-possessed father. He survived but lost a hand and an eye. The demon also burned its emblem into his skin. Those marked by a demon are called curseds and are at risk of becoming possessed themselves, so they are monitored and enslaved by the state-run UCIS. Working as a slave is hard, but Luke prefers it to the possibility of being controlled by a demon.
Then one night, he wakes to find his worst nightmare coming true. His father's demon has come for him. He runs to the only person who might be able to help him: Zack, a cursed who ran away from the state and created an underground community to protect other fugitive curseds. Zack helps him suppress the demon. But as the UCIS closes in on Zack and Luke's demon crafts its own, nefarious plot, Luke realizes that he must take a stand.