Stated first printing, thus. Tight, flat, square, sharp book with light wear and toned pages. First appeared as a serial in Amazing Stories in 1957 and later published in pb by Bouregy. Original title: the Scarlet Saint. 

Earth's elusive masters tolerated only one planet-wide organization - the Scarlet Order of Men. Only the most favored of the People could enter the Institute, as children, to undergo rigorous training. Those unfit for the Order became Blue Brethren, servants, and guides of the People, aiding and instructing them as loyal members of society, under the rule of the benevolent Trisz.

"Like the Bene Gesserit from Frank Herbert’s Dune, Manly Banister has created a far future quasi-planetary romance with and especially compelling depiction of what it would mean to be trained to detect and interpret every nuance of human physiology. In fact this whole short novel is like a pocket version of Dune – what with all the quasi-religious/scientific ideas, the overlords, the secret societies and the deserty planet-ness. Conquest of Earth may have more ideas per hour as any other audiobook I’ve listened to in the last decade.
...There is a lot of other zany stuff going on in this novel: teleportation, trickery, a prophetic computer, and a dose of amnesia (for good measure)."