Serial killers are terrifying. What's even more terrifying than a serial killer is when one of the most notorious ones to ever exist is never caught. Zodiac uses its real life story to tell a chilling tale about the Zodiac killer and his effect on the town of San Francisco in the 70s. The world of the film is recreated so perfectly that it begins to feel less like a movie as it goes on and it begins to seem like you're just watching these events unfold as they happened. The exploration of obsession is something that David Fincher developed in his first major film, Seven, and masters here. The way that the search for the Zodiac killer is conducted references both the professional side and the amateur, which works on multiple levels in the narrative. Fincher's characters become more troubled as Zodiac progresses and the killings actually stop. This allows the audience to see the lasting effects of the killer's efforts, which is far more haunting than seeing them as they take place.