A history of Earth gangsters, published in 1992 and left behind on Sigma Iotia II by the USS Horizon, which the imitative Iotians adopted as the blueprint for their entire society.
Chicago Mobs of the Twenties is the object at the centre of the second-season episode A Piece of the Action. The book, a popular history of organised crime in 1920s Chicago, was left on Sigma Iotia II in 2168 by the crew of the USS Horizon, a century before the Enterprise's visit in 2268.
The Iotians, a bright and highly imitative people, treated it as scripture. When Kirk, Spock and McCoy beam down they find a world of pinstripe suits, tommy guns and rival bosses, where the volume is kept on a stand and referred to simply as the Book.
Kirk repairs the damage in the planet's own idiom, posing as a bigger boss and forcing Bela Okmyx, Jojo Krako and the rest into a single syndicate from which the Federation will take its cut. The episode ends with McCoy admitting that he has left his communicator behind.