Being Or Nothingness

no, not Being and Nothingness; different book mentioned in The Psychopath Test.

Eric Rauchway got some copies. I found an envelope bearing postage stamps from Sweden. Addressed to me in a clear hand, with a note at the corner saying, “Will tell you more when I return!” it contains no letter, only a slim volume by “Joe K”, purporting to transmit the English translation of a Swedish translation of “Sir Arthur Conan Doyle’s ‘Being or Nothingness’, commonly referred to as ‘The Giant Rat of Sumatra’.”The cover art is by M. C. Escher. The flyleaf contains a letter from “The Writer” to Douglas Hofstadter. With a butterfly on the letterhead. No, I am not kidding. So far I count five of my favorite things, and I haven’t got to the title page.

Oooh a PDF. Only 25 pages?

The giant rat of Sumatra is a fictional giant rat, first mentioned by Arthur Conan Doyle in "The Adventure of the Sussex Vampire".[1] As part of the tale, the protagonist, Sherlock Holmes, declares that there is a "story" connected with this rat, presumably a detective case he has handled. The name of the rat and its implied unpublished history were later used in Sherlock Holmes pastiches by many other writers A number of authors of Sherlockiana have endeavoured to supply the missing adventure of the giant rat of Sumatra, either in non-canonical Holmesian fiction, or as references to the tale in other fictional settings. https://en.wikipedia.org/wiki/Giant_rat_of_Sumatra

• The Tale of the Giant Rat of Sumatra is the seventh comedy album produced by the Firesign Theatre and released in January 1974 by Columbia Records.