At around 250 pages, British author Susanna Clarke’s second novel “Piranesi” seems miniscule in comparison to her 800-page debut novel “Jonathan Strange & Mr Norrell.” But with its imaginative world and compelling narrator, “Piranesi” packs a powerful epistemological punch. The book, however, is not without flaws — its portrayal of minority characters ultimately falls short, leaning on worn-out stereotypes of gay men and people of color.