Ella, a humble herb gatherer, possesses mysterious power within her blood that can purify the Blood Plague curse afflicting vampires. She is forcibly abducted by Damian, a ruthless vampire prince, to become his nominal bride and a "walking blood bank". Struggling to survive in the vampire castle rife with dangers and conspiracies, Ella leverages her innate knowledge of herbal medicine and her golden finger—the comprehension of Dao Rhythm, Laws and Artistic Conception—to quietly research the origin of the curse, while engaging in perilous cat-and-mouse games with Damian. As they are forced to spend every day together, Ella discovers that Damian is not as cruel as the legends claim, for he bears the burden of his entire clan’s survival and an ancient secret. Meanwhile, Damian is drawn to Ella’s resilience, wisdom and kindness, and his frozen heart slowly thaws. When the werewolf clans, the Church of Vampire Hunters, and opposing factions within the vampire race all emerge, seeking to seize or destroy Ella, Damian chooses to stand by her side and confront the malice of the entire world together. In the end, Ella not only eradicates the Blood Plague curse entirely but also uncovers her true identity as a descendant of the ancient Moon Priestess. Transcending their transactional bond, she and Damian evolve into genuine soulmates across races, jointly ushering in a new era of peaceful coexistence between vampires and humans.