Police discover a satanic cult is practising human sacrifice, led by cult leader, a man named Carl Drew, in Fall River, Mass. in 1979.

The bizarre 1981 trial of Carl Drew incites fear across the country; the lead detective in the case becomes haunted by his own investigation.

Robin Murphy comes forward to tell her story, for the first time, in a prison interview; her revelations paint a picture of corruption; an additional murder is revealed, previously thought to be unconnected to the case.

While Carl Drew appeals his case, a new witness is discovered; the filmmakers return to meet with Robin Murphy a final time.