In a world where humans and dragons coexist but have been locked in conflict for generations, the Dragon Hunters Guild claims to protect humanity while secretly hunting dragons to extinction. Cassian Drake was raised from childhood by Garran Drake, the leader of the Dragon Hunters Guild, and trained to become the guild’s sharpest weapon against dragons. He firmly believes that dragons are evil, that his mother died beneath dragon fire, and that the great sword and white bone dagger in his hands represent justice.
Until the day he is ordered to execute a captured noble of the golden dragon clan—Aureon Veyr.
Aureon is imprisoned deep within a magma-filled dungeon. His body is covered in scars, yet an unbreakable heart scale still remains hidden in his chest. Cassian drives his white bone dagger toward him, intending to deliver the final blow, but instead accidentally awakens the Heart Scale Oath.
The oath binds their heartbeats together and connects their pain. It also makes Cassian the only person in the world capable of truly killing Aureon. When the Dragon Hunters discover the existence of the oath, they immediately label Cassian a corrupted traitor and lock Aureon away once again.
Garran tells Cassian that noble dragons cannot be killed by ordinary means. Only the person bound by the oath can bring about Aureon’s end. He continues to manipulate Cassian with the lie that his mother died because of dragon fire, forcing him to maintain his hatred toward dragons.
