The movie is based on the real killing events & crime files of serial killer Zodiac during 1968-72 in North California. The movie also shared a link with the same serial killer case known as Scorpio in Clint Eastwood’s 1971 box office hit ‘Dirty Harry’. Unlike the Dirty Harry, the real Zodiac killer as portrayed in this film never caught or identified. It’s perfect gripping film by the master of thrilling psychological dramas- David Fincher. Robert Downey Jr. slowly n steadily making his present felt in every movies & this movie is one more proof of it. Mark Ruffalo & Jake Gyllenhall has done nice justice to the roles offered. But more over everything its razor edge gripping rigmarole (puzzle) of the case & its real to reel clear cut research & direction of Fincher which made the film solid edgy thriller.