Zodiac is a mystery thriller, it is directed by David Fincher. The movie is written for the sceen by James Vanderbilt. It is based on the non-fiction book by Robert Graysmith of the same name. The movie has a stellar cast of Jake Gyllenhaal, Robert Downey Jr., Mark Ruffalo along with Brian Cox, Elias Koteas, Donal Logue, John Carroll Lynch, Chloë Sevigny, Philip Baker Hall, Dermot Mulroney and Anthony Edwards. The movie is regarding Robery Graysmith played by Jake Gyllenhaal, who is obsessed over catching the zodiac killer. The conflict of the movie revolves around obsession, crime and murder.

The movie is set in the 1970s in California. Robert Graysmith is a cartoonist that works in the Chronicle (newspaper).
After the murder of Darlene Ferrin and Mike Mageu, The Chronicle recieves encrypted letter written by their killer who calls himself the "Zodiac". He threatens to kill more people unless his encrypted message is published, which is the secret to his identity. Robert Graysmith is a political cartoonist and he correctly says that the identity is not hidden in the message. Paul Avery (Robert Downey Jr.) doesn't take him seriously.
After another killing, Paul talks to Robert about another letter and starts sharing information with him. When he deciphers one of the letters, its a reference to a video game in which one has to hunt human prey, from this they get an idea that the murderer is a serial killer.
The police detectives suspect a person named Allen, but his handwriting doesn't match the letters that the killer sent. Even though Alllen is ambidextrous but the detectives don't have any physical evidence. Graysmith even visits Allen and they stare at each other. When Robert starts to investigate deeply into the case, he receives calls with heavy breathing. He loses his job and even his wife leaves him over this obsession. Avery becomes an addict. The detectives get transferred. In the end after many years Garysmith's book becomes a bestseller. A prime witness finally identifies Allen but he is long dead and the case is still open.