In "The Zodiac Killer: Case Closed?" we open a new investigation into the mystery surrounding one of history's most notorious unidentified serial killers. Throughout the 1960s and 1970s, the so-called Zodiac Killer terrorized America with the most gruesome attacks and sending bizarre letters with cryptograms. Three of these cryptograms have never been solved. A new team tries to solve the case with the help of a supercomputer. The team will have access to all police documents, witnesses and clues.