For fifteen years, from 1966 to 1981, this man terrorized all of America. A terrible serial killer who sent encrypted, mocking letters to the police and major American newspapers, in which he told the authorities about the crimes he had already committed and promised new, no less terrible and bloody ones; an extraordinary personality; a smart and inventive person; presumably a naval officer who was fluent in codes and encryption; he always signed with a fictitious name - Zodiac. He was never caught. Who was this man really? How many victims is on his conscience? Robert Graysmith, a contributor to the San Francisco Chronicle, offers readers his own version, supported by unique documents that he discovered during his journalistic investigation.