A suspenseful documentation of the search for Zodiac killer, who made the headlines with his apparently random killings and his coded messages to the press as to his identity, whilst killing with impunity, largely in the San Francisco Bay area of Northern California, in the 1970s. The story follows that of puzzle solver and cartoonist Robert Graysmith and is reflected in the somewhat amateurish, if occasionally compulsive, efforts of various resource stretched California police units.