When hematologist Vivian Ye investigates the mysterious death of her sister Talia, the clues lead her to a hidden castle that appears only under the full moon. There, a vampire clan greets her with a terrifying truth: they believe she is their ancestor. Behind the castle lies a cursed laboratory, a history of failed clones, and a three-hundred-year experiment written in Vivian’s blood. To uncover the truth behind her sister’s death, Vivian must confront her forgotten past and decide the fate of everyone trapped in the darkness with her.