Owen Greene holds a powerful gift from the gods in his veins. People like him, called Astrans, are banned from using their power by the governing Legion, who sends out its strongest forces — Core Wielders — to hunt those in hiding. Getting caught means falling prey to the Cleansing — a dangerous ritual used to extract power from those who hold it, only for it to be planted within mechanical spheres called Cores.

Elian Darrow is an elite Core Wielder, loyal to those he serves and diligent in getting what he wants. But when a Cleansing ritual turns dire, Elian begins to lose faith in himself, until he comes across someone who may be the key to the Legion’s darkest kept secret — Owen.

Forced to leave his home behind with a family friend and a rough newcomer, Owen must make his way to safety and before long, Elian is on his trail. But as Owen masters his power, he soon realizes the secrets and shadows that accompany it are just the beginning.