English-born mr. Leeds had his first occult experiences in Istambul in the 1860s. He soon decides to move permanently to the Ottoman capital, change his name to Hieronymous Menkaph and dedicate his life to achieving occult power. A cunning and ambitious man, he teams up with the seductress Nisra, and together they revive the forgotten cult the Children of the Blood Red Fez.
In 1893, Menkaph gets his hands on a Blood Red Fez and soon after he travels to London, where he steals the book The Whispering Fez that can unlock the artifact's secrets. He and Nisra plan to sacrifice a prince in order to summon an aspect of an Outer God and bind him to their will, but their plans are thwarted by allies of Prof. Smith.
Menkaph meets a horrible end in Istambul in 1893 when his Fez-wearing head explodes in the cult's headquarters on the Prince's Islands.