The true story of the Zodiac serial killer makes for an enthralling cinema experience, taking the viewer deep inside a highly complex police investigation.

The murders took place over between December 1968 and October 1968 in Northern California. The killer called himself the Zodiac in a series of taunting letters which he sent to the press; the last letter was sent in 1974. His letters included four ciphers; three of these have never been cracked.

Police interviewed over 2,500 potential suspects, but the case was never officially solved. The San Francisco Police Department reopened the case in early 2007, and the actual police case files provided the background information for the film.

David Fincher directed Zodiac and the overall look and feel of the film is quite similar to the dark and menacing tones of his other films, Fight Club and se7ven. His assured direction provides some impressive aerial tracking shots over the Golden Gate Bridge and the Port of San Francisco before sweeping straight into the heart of the action.

However, despite the subject matter, this film is not a gory countdown of the Zodiac’s victims, showing how each of them died in gruesome detail. Rather, this intelligent, detailed piece of filmmaking painstakingly depicts the ensuing investigation into the murders and the effect that investigation has upon the police officers, the journalists and especially the cartoonist, Robert Graysmith (Jake Gyllenhall) who made it his life’s work to track down the Zodiac.

Robert Downey Junior is excellent as Paul Avery the heavy drinking crime correspondent on the San Fransisco Chronicle. With a cigarette always in his mouth, and a drink never far from his hand, this hard bitten, somewhat sarcastic journalist is the opposite of Robert Graysmith, a self confessed 'Eagle Scout, first class'.

Yet the two make an uneasy alliance as Avery quickly realises how valuable Graysmith’s code cracking skills will prove to be in investigating the case.

Robert is young, eager and full of drive and ideas. Far from frequenting bars, as Avery does in his spare time, Graysmith reads books and solves puzzles. Although at the start of the film, he is a cartoonist on the San Francisco Chronicle, he finds himself passionately drawn to the case. He becomes totally immersed in the twisted world of the Zodiac killer, to the point of losing his family.

The film shows how the Zodiac left behind not just dead victims, but living ones as well. It depicts in sad, intricate detail the men who became so obsessed in cracking the case that they ended up losing their lives to the killer in a different way; losing their jobs, their famillies, the lives they had before the murders totally destroyed.

Despite the inevitable open ending, this is a very intense two hours forty minutes. Indeed, there is so much information and detail to absorb, you may well come out of the cinema feeling like you need to see it again.