Written by James Vanderbilt and based on two books by Robert Graysmith, Zodiac is the story of the search for the serial killer who terrorized the San Francisco Bay area in the late 1960s and early 1970s. The film begins with the initial murders in 1969. A stalker spies a young couple parked in an isolated lovers' lane and calmly guns them down. Subsequently, the killer catches a couple on a picnic, ties them up and then stabs them. These acts of pointless violence are horrific, but Fincher doesn't linger on them, and, in fact, probably renders them in sanitized detail. He's interested less in the killer than in those who pursue the killer.
The Zodiac murders were sensational because the killer initially went to such lengths to promote himself. He named himself and sent letters to San Francisco newspapers taunting the police efforts to apprehend him. Many of the killer's letters included coded pronouncements and threats. He claimed responsibility for murders he didn't commit, and after nearly being caught when he shot a cab driver, he announced that he would continue to kill but would no longer communicate about his activities. He was never caught, and whether other unsolved killings were his evil handiwork remains a matter of speculation.
Those who pursued Zodiac are detailed in the film as two policemen, an investigative reporter and finally Graysmith (Jake Gyllenhaal) who is at first only initially involved with the case as the political cartoonist for the San Francisco Chronicle. The cops are David Toschi (Mark Ruffalo) and his partner Bill Armstrong (Anthony Edwards); the reporter is Paul Avery (Robert Downey Jr.). The focus and drive of all these men is beyond dispute. The clues point to serious suspects, more than one unfortunately. But they are never able to make a satisfactory case. Worn out, Armstrong finally asks for a transfer out of homicide. Repeatedly frustrated, the charismatic and colorful but high-maintenance Avery finally surrenders to alcoholism. Toschi soldiers on but eventually is transferred out of homicide as well. In the end, only Graysmith perseveres, and he pays for his obsession with the case by sacrificing his job and his marriage.
Zodiac includes Fincher's expected visual flourishes in an evolving palette of colors and fascinating period detail that carefully reconstructs the San Francisco skyline of the era. But the narrative marches forward in such a matter-of-fact way toward its ultimate lack of conclusion that we may miss what the director is up to. Despite a common darkness of vision, Seven, The Game and Fight Club are all artful constructs, each in its own way a trick offered as a diversion and in that way a delight. They are the work of a brilliant pessimist. Life is dispiriting or worse, the films seem to say, but that doesn't deprive us of our fantasies, at least not of the magician-filmmaker's fantasies. Zodiac abandons the tricks or, maximally, reserves the tricks for the villain. Our heroes, wonderfully individualized by the terrific cast, have only their resolve and their sweat to offer. Some take refuge in surrender, others in refocus. But even for those who carry on, their efforts are insufficient.
Or their efforts are insufficient for them to prevail in the way we are used to heroes, particularly Hollywood heroes, prevailing. Toschi never loses interest in the Zodiac case, though he does become convinced that no evidence will ever come to light to justify an arrest. Graysmith manages to step beyond that frustration into the purest exertion of existential will. It is enough, he asserts, to know. The victory, indistinct and uncertain as it is, lies not in the truth, which is so stubbornly elusive, but in the unrelenting search from which the truth may perhaps be glimpsed.