In 1977, the neighbourhoods of Los Angeles were turned upside down by a series of gruesome strangulation murders, leaving the police to face mounting public pressure to identify the faceless killer and protect the city's women.

Two college students are found dead in Bellingham, Washington a year after the Hillside Strangler murders in Los Angeles come to an end; local security guard Ken Bianchi arouses suspicion after being caught in a string of lies.

An explosive revelation in Bellingham and clues in LA lead investigators to a second Hillside Strangler suspect; as authorities close in on Ken Bianchi's alleged accomplice, a clue from his psychiatric interview tapes leads to a stunning discovery.

As Angelo Buono's trial begins, all eyes are on Ken Bianchi as the state's key witness, but as Bianchi's credibility crumbles, so does the prosecution's case.