A daring study that uncovers the real nature of the Priory of Zion, one of the secret societies that is still alive nowadays and that dominated medieval politics from behind. Given the numerous absurdities which have been written lately about this society, the author reveals the other secret reality of this Priory. Its alleged Templar heritage the secret archives, the gnosis ( a Church of John, superior to Peter's) and the claim for P.Plantard, of arguable blood & lineage.