Based on the book of the same name by Robert Graysmith and the true events of the notorious Zodiac killer of the late 1960s and 70s San Francisco Bay Area, Zodiac is a thriller murder mystery starring Robert Downey, Jr., Jake Gyllenhaal and Chloë Sevigny. It begins when a couple is mysteriously attacked by and unseen assailant at a popular secluded meeting spot in Vallejo, California, a town in the Bay Area. A month later the mysterious killer begins to send taunting and encrypted letters to the San Francisco Chronicle newspaper, but directed at the police. The political cartoonist Graysmith (Gyllenhaal portraying the author of the book the film is based on) takes an interest in the case and the letters but is not taken seriously by his co-worker Paul Avery (Downey Jr.) or the police because of his occupation. However, when he cracks one of the killer's encryptions and the killer repeatedly strikes again and continues to taunt the police, the case comes too close to home for Graysmith as he gets closer and closer to the identity of the killer over the years but it ends up costing him much more than he anticipated.