One of the first dystopian science fantasies, this novel features a grey dust from an ancient glass vial which is capped with a silver figure of Cerberus, the 3-headed mythological dog that guarded the gate to "Pluto's realm", that is, to Hades. The fine dust transports anyone who inhales it to a totalitarian Philadelphia of 2118 AD. It was written by Gertrude Barrows Bennett (1883–1948) under the pseudonym Francis Stevens. Bennett, the first major female writer of fantasy and science fiction, has been called "the woman who invented dark fantasy."