In the late 1960s and early 1970s, law enforcement discovered a pattern of murdered hitchhikers and young men; their investigation led them to an unassuming aerospace engineer, who lived a double life as a sadistic killer.

With Patrick Kearney behind bars, police realize another predator is on the loose; an investigation leads to "The Freeway Killer" and his torture chamber on wheels; the murders suggest the work of more than one single killer.

With Bonin behind bars, law enforcement hopes the nightmare is over-until another wave of freeway murders shatters their illusion; this third killer is the most methodical of them all and, if not for a random police check, might have evaded police.