The Three Impostors is an episodic novel incorporating several weird stories, including "The Novel of the White Powder" and "The Novel of the Black Seal", and culminates in a final denouement of deadly horror, connected with a secret society devoted to debauched pagan rites. The three impostors of the title are members of this society who weave a web of deception in the streets of Londonrelating the aforementioned weird tales in the processas they search for a missing Roman coin commemorating an infamous orgy by the Emperor Tiberius and close in on their prey: "the young man with spectacles". Also included are: "The Novel of the Black Seal" A precursor of H. P. Lovecraft in its subject matterthe protagonist gradually uncovers the secrets of a hidden pre- and non-human race hiding in the Welsh hills, and the true nature of a hybrid, idiot child fathered by one of them. "The Novel of the White Powder" A man's behavior takes a strange turn after he starts taking a new prescription. His sister doesn't know if this is a good thing or a bad one. Contents: Adventure of the Gold Tiberius. The Encounter of the Pavement. Novel of the Dark Valley. Adventure of the Missing Brother. Novel of the Black Seal. Incident of the Private Bar. The Decorative Imagination. Novel of the Iron Maid. The Recluse of Bayswater. Novel of the White Powder. Strange Occurrence in Clerkenwell. History of the Young Man with Spectacles Adventure of the Deserted Residence. Arthur Machen (1863-1947) was a Welsh author and mystic of the 1890s and early 20th century. He is best known for his influential supernatural, fantasy, and horror fiction.