The story follows a down-on-their-luck couple who discovers a serial killer's film reels. They decide to take the law into their own hands, risking everything for the chance at a $100,000 reward. It isn't long until they find themselves in the killer's lethal cross-hairs.
Over 40 years since the infamous Zodiac killer terrorised inhabitants of San Francisco and surrounds, three people stumble across homemade films of some of his murders. They then set out to track him down.