I just read "The Heart is a Lonely Hunter" by Carson McCullers and "Darkness at Noon" by Arthur Koestler. Both novels were listed among the top 20 English language novels by the Modern Library, and they were published in 1940 and 1941, respectively.
"Darkness at Noon" is an expose of Stalinism. The protagonist (Rubashov) is a devoted communist who fought in the Russian Revolution, but has fallen afoul of the current regime. He is imprisoned, questioned, forced to sign confessions, and executed.
The novel feels a little dated, to me. Everyone now knows the evils of Stalinism. Nonetheless, Rubashov is an interesting character -- an idealist who is conflicted about loyalty to the "Party", or loyalty to the goal of world revolution. Apparently, Stalin (known as "#1" in the novel) wanted to hunker down and abandon world revolution, and had anyone whose opinion differed shot.
Rubashov is an interesting chap, and when his questioners want him to sign a document admitting that he tried to assassinate Stalin (a crime of which he was not guilty) he is willing to sign, but objects to the stupidity of the plot to which he is confessing. He doesn't want to look like a fool.
The novel is a short, easy, and dramatic read.
"The Heart is a Lonely Hunter" also involves pre-WWII communism. Set in a mid-sized city in the South, the novel revolves around a deaf-mute named John Singer. Singer is best buddies with another deaf mute who is fat, stupid, and ends up becoming a criminal and getting sent to the State mental institution.
Several locals then befriend Singer -- an itinerant commie labor agitator (Jake Blount), a local restaurant/bar owner (Biff Brannon), a black physician (Dr. Copeland) and a 12-year-old girl (Mick Kelly). Singer is serene -- he can't talk well (except in sign language), but he can read lips. So he is the ideal listener for his four friends - and he's a basically kind soul. Like the labor organizer, Dr. Copeland is a Marxist. He is also a proud, educated man, whose wife and children left him years ago. They live with Grandpapa, who owns a small farm. The Dr. cannot hide his disappointment in his children -- why do they not educate and improve themselves? Why do they seem to merely accept their (and their black brethren's) lot? Yet Granpapa's farm is accepting and communal -- it represents the uneducated and unidealistic communism of poverty. Still, when Grandpapa dreams that an angel descends and touches all the family members, turning them white, Dr. Copeland leaves in disgust.
Mick Kelly is a central figure in the novel, coming of age. She has a "Prom Party" when she's a freshman in high school, which involves dressing up and then "promenading" around the block with young boys. I assume that school "Proms" may have stolen the word from this kind of party.
In the end, Singer's deaf-mute friend dies in the mental institution, and Singer, despite his friendship with these four far more interesting people, is despondent. Why does he like his mentally handicapped friend so much? It seems to me the reason is that his friend can understand sign language. Just as the four other main characters like Singer because he listens to them, Singer needs someone to whom he can talk -- even someone as unattractive as his fat friend.
McCullers wrote the novel when she was only 20 years old (it was published when she was 23) and it was an instant hit. Some of the portraits of the black characters seem a little dated and racist, but the novel remains dramatic, insightful and well worth reading.