Often compared to THE TRIAL by FRANZ KAFKA, DARKNESS AT NOON is a semi-allegorical novel about the Stalinist "show trials" and purges of 1938 in the Soviet Union, during which intellectuals, powerful & popular rivals, and old Party Bolsheviks were either executed or condemned to long prison sentences, although the book never mentions in which country these events occur, nor the name of the political party. The main protagonist of the story is Rubashov, a loyal Party believer for many decades -- which seems to be his main crime:  he is one of the old Bolsheviks and Party idealists, for whom the Party has outgrown.  In short -- he has become an embarrassing inconvenience, and his execution is almost certain.  The novel takes place almost entirely inside the prison in which Rubashov has been detained, and leads up excruciatingly and even maddeningly to his eventual fate.

As an extra side note, BOB DYLAN also swiped from the book very early in his career, in the first line from his 1965 song "IT'S ALRIGHT, MA (I'M ONLY BLEEDING):