Isabella is an ordinary high school student, but she harbors a huge secret: she is a vampire. Ten years ago, she was on the brink of death during a tragic accident when a mysterious vampire, Claes, saved her life through an ancient vampire ritual known as the "Blood Sacrifice," turning her into a vampire. However, due to memory loss, she has no recollection of her vampire identity or Claes' act of saving her life. She lives a seemingly normal life in London, but Claes constantly appears in her life, making things complicated. Claes is not only her savior but also a domineering doctor with a cold and arrogant personality. Despite Isabella's hostility toward him, Claes exhibits a powerful sense of possessiveness over her. He even uses her secret as leverage to force her to move into his home. Gradually, Isabella begins to uncover the truth about her past. She learns that years ago, her heart condition nearly claimed her life, but Claes took a significant risk to save her using the ancient vampire "Blood Sacrifice," which made her immortal. Although Claes appears distant and unfeeling, he has deep feelings for Isabella and has been protecting her all along. However, Isabella is unwilling to accept this fate. She desires to break free from Claes' control and reclaim her freedom, yet she struggles with her complex feelings for him. As their relationship continues to evolve, a series of vampire murders start occurring in London, and the mastermind behind them may be connected to Claes' family...