The Flying Saucer Investigators is a book of history. It's about the people involved in the mystery of the flying saucers, mostly the investigators, but also the witnesses, some of whom were profoundly affected. The period covered is what has been called "The Golden Age of Flying Saucers", which begins in 1947, after the sighting that year by businessman pilot Kenneth Arnold, and ends in 1969, with the termination of the US Air Force's investigation, which existed for most of its duration as "Project Blue Book".

The investigators ranged from kids with saucer clubs to serious-minded individuals with connections in government. There were military personnel assigned to take flying saucer reports and follow up on them, and the US Congress was moved to hear arguments for a federally funded study of flying saucers on two occasions. The history of this "Golden Age" is presented using newsletters, magazines, case files, official documents, newspaper articles, film footage, and archived recordings from television and radio. Some of the cases the investigators looked into are presented using nothing but the facts as they were recorded, without speculation or sensationalism, and even the die-hard skeptic may be left wondering by many of them.