A kind-hearted human woman, Isla Wren, falls in love with the powerful Vampire King, Dorian Nox, but a jealous vampire countess fabricates a blood prophecy that convinces him Isla will one day betray and kill him. Heartbroken and abandoned, Isla secretly gives birth to their half-vampire daughter, Ruby, and spends two years hiding her while searching for a way to suppress Ruby's dangerous royal bloodline. When Ruby's illness forces Isla back into the vampire kingdom, she is repeatedly thrown together with Dorian, who still believes she deceived him but cannot stop protecting her or being drawn back to her. As Dorian slowly uncovers clues that Ruby is his daughter, old misunderstandings, political schemes, and jealous rivals threaten to tear the family apart just as the truth is finally within reach.
