The Golden Dawn

In Chapter Two of The Dear Departed, my hero, Jonathan Bradshaw, uses three knocks with passwords to access the fictitious Isis-Nephthys lodge room. Sharp-eyed readers will recognize these passwords as those used in the Golden Dawn neophyte ritual described in The Complete Golden Dawn by Israel Regardie published in 1970.
So what is the Golden Dawn?
The story begins in the year 1887 when a Freemason, Rosicrucian and occult scholar, Dr. William Wynn Westcott, came into possession of a manuscript written in a strange cipher. The cipher, called the Trithemius cipher, was developed by German author and monk Johannes Trithemius in 1508. It uses a letter square with the 26 letters of the alphabet following 26 rows of additional letters, each shifted once to the left. The resulting text looks like a random string of letters, except that the letter frequencies are just shifted.
Esoteric manuscripts during the Middle Ages and early Renaissance were often written in cipher. During the time that Trithemius developed his cipher, the Inquisition was a very powerful force in most of Europe. Manuscripts containing magical lore could be very dangerous to the owner if discovered by ecclesiastical authorities, so they were written either in various forms of coded text or in elaborate symbolism which would be incomprehensible to anyone not schooled in esoteric lore.
The cipher manuscript, when decoded, turned out to be a series of rituals which could be used for initiating students into a hierarchy of ten levels or grades within a magical lodge. The grades, ranging from neophyte (0=0) to Ipsissimus (10=1) corresponded to levels of knowledge that an aspirant was expected to have in the arcane arts of Qabalah, astrology, tarot, geomancy and alchemy. They provided a framework for a kind of magical journey that enabled an aspirant to ascend up the ten levels of initiation while acquiring increasing amounts of esoteric knowledge and achieving ever more powerful magical skills.
There was no author listed on the document, only an address with an invitation to communicate with it. Westcott did so. The address turned out to belong to a Countess named Anna Sprengel who had been a member of a secret Rosicrucian lodge in Germany. During the resulting correspondence, Frau Sprengel authorized Dr. Westcott and his associates to start their own magical lodge. With these rituals, along with the arcane lore that went along with them, Westcott and his associate S. L. MacGregor Mathers founded a magical lodge called the Order of the Golden Dawn. The first lodge, called the Isis-Urania Temple was founded in London in 1888. It was followed by a number of offshoots, both official and unofficial, throughout the world that continues to the present time.
The Isis-Nepthys lodge is, of course, fictitious. However, esoteric societies such as the Golden Dawn became more common on both sides of the Atlantic as the 20th century progressed. They constituted part of a general ‘occult revival’ filled with practitioners -- spurious as well as genuine -- of astrology, alchemy, spiritualism and magic. Archeological discoveries sparked a renewed interest in ancient cultures worldwide and many prominent artistic people were members such as actress Florence Farr, writers of tales of imagination, such as Arthur Conan Doyle, Algernon Blackwood, and E. Nesbit and visionary poet William Butler Yates.