Sarah's best friend Victoria surprises her with a genetic testing kit for her birthday, so she can discover more about her family history. Victoria, however, is brutally murdered that night. Sarah receives a knock on her door some weeks later, and it is the cops. As their homicide investigation drew to a close, they decided to run the killer's DNA through the genetic testing company's database and discovered a match: Sarah. As it turns out, Sarah's best friend was murdered by a family member... who's, however?