In the late sixties, a serial killer calling himself the Zodiac terrorized the San Francisco Bay Area, committing brutal, random attacks, and bragging about them in letters to the San Francisco Chronicle.

In Santa Rosa, fifty miles to the north, investigators Manny Bruin and Mick Millian were asked to tail potential suspect Byron Avion, an odd, portly man admittedly obsessed with the Zodiac. He had other eccentricities as well, not the least of which was his large collection of cardboard boxes, carefully stacked and tied shut with white nylon rope.

But peculiar habits do not a criminal make - that is, not until the bodies of young female hitchhikers began appearing in ditches, tied up with white nylon rope. That and a dozen other connections convinced Bruin and Millian that Avion was the Highway 101 Murderer, a Zodiac-style killer who prowled the Santa Rosa area.

Despite the connections, a decade-long investigation was unable to connect Avion to the crimes, or connect Zodiac to the northern murders. Bruin and Millian eventually became so frustrated that they dubbed Avion "Suspect Zero," and hoped for something to break the case open. When that break finally came, it re-wrote the book on homicide investigations and forever changed the direction of each man's life.