A family torn apart by their grandparents' murders. Two decades later, a cold case detective takes on the case that has haunted him since he was a child. When he makes a big break in the case, he must race to solve it before the family takes matters into their own hands.

A killer authors a book about his con-man past that becomes the key to solving a 29-year-old cold case of two high school sweethearts–and three other cold case murders–leading police to believe he could be the Zodiac Killer.