A woman discovers shocking evidence implicating her brother in multiple disappearances. A devoted father is suspected of attacking women in his neighborhood. A son believes his stepmother concealed clues about his father's death.

Lives are turned upside down when the twisted predators in these cases turn out to be THE DEVIL YOU KNOW. Upon looking in her brother's bag, a woman finds devastating evidence linking him to the disappearance of multiple women, a devoted father of three may be attacking women in the neighborhood, and a son suspects his stepmom buried evidence of his father's death in her garden.