Sierra Barter begins investigating her step-grandfather Jim by reaching out to family members, some of whom she had not spoken to in years. By interviewing Jim's ex-wives, children, and stepchildren, Sierra begins to put together a horrifying image of the man her step-grandfather was and the terror that he inflicted on his own family.

Jim Mordecai was a revered teacher to most, but to others, he was a monster. Sierra looks deep within herself and questions if Jim’s crimes may have escalated. A curious family heirloom launches Sierra down a rabbit hole where a series of unsolved murders has her asking if Jim could be the killer.

Sierra’s uncle shares a disturbing story further implicating Jim and a private investigator urges Sierra to find evidence. After Sierra searches through family storage, she learns the truth about a night that changed her family forever, and in turn, takes her investigation into a different direction.