The Sins of the Cities of the Plain is an avant-garde opera based on the homonymous book which was first published in 1881 by William Lazenby and republished by Leonard Smithers in 1902. The book appears to be the memoirs of Jack Saul, an actual male prostitute of Irish birth who lived in London. In the book Saul is picked up on the street by a Mr. Cambon. After they have dinner, Cambon invites Saul to recount his life story.
The libretto, an hour-long monologue, is written (for the first time in opera history) in Polari, a crypto-language spoken by the homosexual community since the end of the XIX in the big British metropolises (especially London) to avoid being overheard and persecuted by a society where homosexuality (sodomy) was a crime. Although Jack Saul really existed, the novel is not attributed to him though it sources from his life experiences (common knowledge amongst Victorian homosexual circles) as well as actual Victorian underground sub-culture and identities.