Just got my copy of the book, thanks for the heads-up on it.
Chapter 6 has a section titled "A new global religion" which talks about Vallee's Messengers of Deception. It says the book "describes his investigations into an occult group called the Order of Melchizedek" and then goes on to give an overview of his multiple encounters with groups calling themselves that & also some standard background history of the name.
I notice that a few pages later, the Solar Temple is talked about: "the Orders' doctrines also emphasize the importance of the secret priesthood of Melchizedek""
That's a new one on me! The Solar Temple incident continues to amaze me. A BCCI-connected arms-dealing pseudo-Masonic suicide-cult.