"Deadly Cults" dives into unhinged murder cases in which investigators uncover and expose the dark world of cults that kill. These four-hour long episodes look at a variety of things, including a self-proclaimed prophet who convinces his followers to murder an innocent family, and a vampire coven searching for a sacrifice. The series explores how power and manipulation can lead to extreme actions. Each case is recounted through interviews with investigators, former cult leaders, and the family and friends closest to the victims. Look behind the eyes of cult leaders and the psychology behind them as they exploit fear and hatred in their followers' minds and hearts.