By Caleb Crain, from Necessary Errors, to be published next month by Penguin.

According to the pages on Eastern Europe that he had torn from a guide to gay life abroad purchased in Boston — burying the rest of the book at the bottom of a garbage bag full of food scraps soon after, so that no one would inadvertently come upon its advertisements for massage parlors and bathhouses — there were two gay bars in Prague, and the one not described as “rough” was to be found in a street one block long near the foot of Wenceslas Square. After…