In the late 60's and early 70's, the Zodiac killer claimed responsibility for a series of murders in and around San Francisco, taunting the police and the papers with cryptic letters. After detective David Toschi (Mark Ruffalo) fails to conclusively crack the mystery the case becomes dormant, until a young cartoonist (Jake Gyllenhaal) from the paper takes up the challenge.
It's been five years since David Fincher's last effort (the overblown and disappointing Panic Room), and with the opening 20 minutes of Zodiac it's clear he has a far more inspiring story to work with here. The film quickly demonstrates it's support for the Scorcese style of film-making, with the period setting of the story evocatively re-created, some great montages and a high volume soundtrack that works exceptionally well - using Santana, Donovan and other 60s icons, to (relatively subtly) create a believable world for the story to exist in.
Fincher seems to have found his feet a bit more that usual here, steering away from his move overt technique tricks and producing an elegant film, with some excellent directorial flourishes. The opening shot sets the scene superbly in July 4th California, there's a magnificent tracking shot of a taxi from above, and a similar shot following of the first letter to arrive at The Chronicle newspaper.
The acting throughout is superb, but some of the performances are restricted by the slightly clunky format of at least the middle of the film. As the timeline shifts forward at a variety of rates ('2 months later', '20 minutes later', '4 years later') it becomes hard to sustain the supposed 'reign of terror' that the killer had over the state, but once things settle down it finds it's feet nicely. That unfortunately leaves Robert Downey Jnr's character a bit redundant, and focus shifts over to cartoonist Robert Graysmith's developing interest in solving the case. Strangely, that provides a lot more suspense and twists in the plot, with the unsolved nature of the case leading to a bit of speculation, but also some surprises.