An explanation of the usual reasons for confusing IFOs (identified flying objects) with UFOs and a survey of the tools used to investigate reported UFO sightings.
I don't know why people took this work to be a serious look at UFOs, it is not, only a guy on the phone having opinions about cases he could barely investigate. He claims he is not biased, but his writing betrayed he was very much so. Interestingly, in the past he had challenged people like Klass and others like him, but on this book he act in very similar fashion.