Dark Secret. Number 15 in series

Colby Jansen has been raising her step-siblings, Ginny and Paul, single-handedly since her beloved stepfather, Armando Chevez, died. She's also been working herself into the ground to keep the family ranch running, but now she's got a real fight on her hands. Members of the Chevez family, along with two of the powerful De La Cruz brothers, for whom Colby's family has worked for centuries, arrive at her door, intending to take custody of the children and dispose of the ranch.
For ancient Carpathian Rafael De La Cruz, the world has become dark, and he is in danger of turning vampire. But when he meets Colby, he knows immediately that she is the one who could save him. Colby finds the handsome Rafael threatening but, against her better judgement, she is also irresistibly drawn to him. They quickly find that they are an equal match in terms of fiery temperament and stubbornness, but when an ancient and powerful vampire begins stalking Colby and her family, she and Rafael combine forces to combat a deadly evil...