- Directors: David Fincher
- Producers: Mike Medavoy, Brad Fischer, Arnold Messer, James Vanderbilt
- Writers: Book, Robert Graysmith, Screenplay, James Vanderbilt
- Genres: Biography, Crime, Drama, Thriller
- Actors: Jake Gyllenhaal, Robert Downey Jr, Mark Ruffalo, Anthony Edwards, Brian Cox
The film starts in July 1969 with the Zodiac killerâ€™s second attack, the shooting of Darlene Ferrin and Mike Mageau at a lovers’ lane in Vallejo. Mageau survives while Ferrin dies from her injuries. A letter written by the Zodiac arrives at the San Francisco Chronicle in August of that same year.
Paul Avery (Robert Downey Jr.) is a Chronicle crime reporter. Robert Graysmith (Jake Gyllenhaal) is a political cartoonist there. The newspaper receives encrypted letters that the killer sends, taunting the police. Because of Graysmith’s status as a cartoonist, he is not taken seriously by Avery and the editors and is excluded from the initial details about the killings despite his interest in the case. In particular, he is drawn to the encrypted code that is included with the letters and is given access to one. When he is able to crack one of the codes and makes several correct guesses about the killer’s actions, Avery begins sharing information with him.
The Zodiac killer stabs Bryan Hartnell and Cecelia Shepard (Pell James) at Lake Berryessa in Napa County. Shepard dies as a result of the attack. Soon afterwards, cab driver Paul Stine is shot and killed in Presidio Heights. San Francisco police detectives Dave Toschi (Mark Ruffalo) and his partner Bill Armstrong (Anthony Edwards) are assigned to the case, liaising with other detectives such as Jack Mulanax (Elias Koteas) in Vallejo and Ken Narlow (Donal Logue) in Napa. The killer, or someone posing as him, continues to toy with authorities by speaking on the phone with celebrity lawyer Melvin Belli (Brian Cox) when he makes an appearance on a television talk show. Avery and Graysmith form an alliance, delving deeper into the case.
Final title cards, however, inform the audience that Allen’s DNA did not match samples gathered from the Zodiac letters.