Welcome to the 70s. There's a serial killer in San Francisco, and he always manages to stay one step ahead of the authorities. The cops can't catch him, and the psycho keeps surprising them with all kinds of weird messages. Pretty much the whole town is obsessed with this murderer and every single policeman, reporter, and regular citizen wants to bring him to justice. Heavily based on a true story, Zodiac follows the actions the detectives and the reporters took in order to protect their loved ones and find the maniac's weaknesses. The Zodiac - that's what the locals call him - has never been seen, and people start to think that it's more than one man/woman. It's up to a cartoonist to figure this thing out.