Zodiac is not a thriller in the conventional sense. It does not build to a resolution, because the Zodiac case never resolved. What it builds to instead is something rarer and more honest: the understanding of what obsession actually looks like, how it hollows the obsessed from the inside while the world moves on.

Robert Graysmith (Jake Gyllenhaal), the cartoonist at the San Francisco Chronicle who became obsessed with the case, is the film’s center. His obsession destroys his marriage and his career. He solves nothing. But he cannot stop. Mark Ruffalo as Detective Dave Toschi and Robert Downey Jr. as journalist Paul Avery provide the film’s other perspectives, men who got as close as anyone and no closer.

Fincher’s direction is the opposite of flashy: long takes, static camera, real locations, documentary clarity. The film respects the people involved and respects its audience enough to withhold easy satisfaction.

At 157 minutes, Zodiac is long. Every minute is warranted. It is one of the great American films of the 2000s.