From 1966 to 1978, the Zodiac Killer claimed victim after victim in the San Francisco Bay area, repeatedly taunting law-enforcement authorities with direct messages bragging about his deeds. The killer is officially blamed for six murders, but claimed to have killed some 37 people and could have been responsible for as many as 50. When Zodiac starts killing again, the son of the broken journalist who tracked his every move and the retired cop who never caught him, continue the search to find the notorious serial killer.