Seren De Salvo sacrificed the life she wanted for the life she was born to live. In her new role as the moon goddess and wife to Orion, Seren struggles to control her powers and her lingering feelings for her former fiance, Antonio. When she is ambushed by a prince of Hell, Asmodeus, Seren discovers the lives of the past moon vessels were more entangled than she could have dreamed.

After a mission to destroy the evil Obsidian coven goes wrong, Seren sinks into a deep depression, seeking refuge in the most unlikely of places ... Castle Resnov, where Asmodeus resides. As Seren comes to terms with the path she now walks, she learns to weaponize her power, strength, and knowledge, and uncovers a sinister alliance between Obsidian and Lucifer, the Prince of Pride.

Seren and her family must form an alliance with the other princes of Hell to stop Lucifer from acquiring the power he has sought for millennia. But as Seren fights to protect her coven, she must also battle her growing feelings for an unexpected ally. With the fate of the world lingering in the balance, Seren must find a way to be true to herself while saving those she loves.