And Then There Were None

Sarah Morgan's ancestors have been disappearing for centuries. Her family line would have died out a hundred years ago, except for the fact that most didn't die until after they had children. The danger to her family would have been more obvious if everyone on both sides had disappeared, but that was not the case. Only one bloodline running through her family tree was in danger.
A stranger to her, elderly Howard J. Puckett has been investigating her family line for reasons of his own. He sees the danger to the remaining members, and sets out to warn them. Sarah doesn't believe him until her cousin is brutally murdered, and her sister disappears suddenly. Puckett has a theory about her bloodline, and has collected years of documents to back it up. Sarah and Puckett join forces and try to gather the remaining members of the bloodline so they can put their heads together and discover who is behind this mystery. Puckett believes it is a cult, because no one man could live as long as these murders have been taking place.