“The Delusive Cartographer,” a fantasy short story by Rich Larson published in Beneath Ceaseless Skies in 2015, plays with the familiar trope of a lost treasure map. In this story that map is hidden in a prison, which the story’s two rapscallions must break into in order to retrieve the map. Larson throws in more than one plot twist to confound things; the final paragraph’s reveal is well set-up but still surprising.
Related: Fiction About Maps: A Bibliography.