When an ancient and powerful vampire escapes his imprisonment in Tatarus, Princess Celestia calls in her most trusted champion: Special Agent Sweetie Drops... but is there more to the story? Why is Celestia so bent on having this vampire destroyed? What connections does he have with Princess Luna? What is the story behind this vampire named Roma Heart?

All Sweetie Drops knows is that, after four years of deep cover, she has a new mission.