From the director of 'Se7en' and 'Fight Club', 'Zodiac' (based on a true story) promises much, if only from a glance at the credits and, as thrillers go, this one is right up there.

After a spate of murders across the San Francisco area beginning in the late 1960s, panic begins to set in and curfews are imposed. It is suspected that a fame-hungry serial killer is responsible, with the alleged assailant leaving calling cards in the form of cryptic ciphers and referring to himself as Zodiac in all correspondence with police through the media.

Inspectors David Toschi (Ruffalo) and William Armstrong (Edwards) take charge of an investigation which will prove painful in the years ahead. Forensics is not the resource that it is today and society is not populated with closed-circuit television cameras. Brick wall after brick wall leaves the public fearful and disgruntled and the media pointing the finger of blame at the police for not making a breakthrough.

Covering the case for the San Francisco Chronicle is alcoholic journalist Paul Avery (Downey Jr). Shuffling around Avery's desk in the hope of trying to help solve the ciphers is nerdy, withdrawn cartoonist Robert Graysmith (Gyllenhaal), who develops a certain obsession with the details of the case. Suspects come and go and are eliminated due to lack of evidence, frustratingly so for the police, who believe they have the right man on more than one occasion but are hampered by a lack of communication within their own units and sketchy forensic evidence.

'Zodiac' teases its story out over a lengthy duration, which adds to the feeling of frustration and hopelessness being portrayed by its central characters. The action is slow-moving and the passing of time quite natural due to the longevity of the film, yet it never feels like the plot is dragged out.

Some superb acting shines through here, most notably from Jake Gyllenhaal, as the slightly introverted, well-intentioned cartoonist, who pokes his nose into the investigation so many times that he becomes completely consumed with the case, at the expense of his family life. Robert Downey Jr is also on-form as the arty hack, who boozes to function, and Mark Ruffalo really steps up to the mark as the detective restricted by the limitations of resources available to him.

'Zodiac' is a must-see. Fans of the thriller will lap this up but, because the movie doesn't rely on blood and guts or extreme violence to get the horror of the crimes perpetrated across, newcomers to the genre will also appreciate its meticulous attention to detail in the production of an utterly compelling story, without the need for gore.

'Zodiac' really gets inside the minds of all the big players here, what drives them and what eventually sinks them. And to its credit, what it often leaves unsaid provides its strongest moments.

Linda McGee