Arthur Koestler’s 1940 novel Darkness at Noon is a masterpiece. Although its inspiration—via revulsion—was Stalin’s purges of the mid-to-late 1930s, the book’s story, relevance and interest still resonate. The action takes place in a snow-bound prison where political criminals—revisionists, Old Revolutionaries, independent thinkers and those whose careless words revealed bourgeois or subversive tendencies—are first interrogated before being condemned to another prison or shot. The main character, Rubashov, is a senior, long-serving Party member—a decorated hero of the revolution—who imprudently conjectured in conversation with a colleague that removing No.1 (the ruling dictator) might restore the purity of the revolution. Arrested, locked…