Blackveil Castle hides a terrifying secret beneath its haunted halls: an ancient Seal imprisoning a soul-devouring entity known as the Hollow Saint. For centuries, Lord Cassian Veyl—the feared Night Regent—has maintained the ward through bloodshed and sacrifice, convincing himself the atrocities are necessary to save the world.Then Sera Ashbourne arrives.Defiant, sharp-minded, and unaware of the dangerous power sleeping in her blood, Sera awakens something Cassian has spent centuries dreadingBut Sera’s rare Veilfire magic can only awaken through intimacy with her mate—and it may be powerful enough to replace the blood sacrifices sustaining the Seal. Or destroy it completely.As desire turns into obsession and secrets rot through Blackveil’s walls, Sera must decide whether to trust the monster protecting her, while Cassian faces a choice he has never been capable of making before:Sacrifice love to save the kingdom—or risk the world to keep her alive