Some time back I did a search of lists of the type "Best 100 Novels of the 20th Century" looking for additions to my "To Read" list. These three I have not read so, for me, their only known merit is that they appeared in such lists

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Darkness at Noon, Arthur Koestler, approx. 200 ADE pages. The breaking of a man tried for treason in a dictatorship he helped create, through to the making of his false confession.
https://en.wikipedia.org/wiki/Darkness_at_Noon
A Bend in the River, V. S Naipaul, approx. 260 ADE pages. The attempt and failure of the character establishing himself in the darkness of a post colonial African country fallen into endemic dislocation.
https://en.wikipedia.org/wiki/A_Bend_in_the_River
Appointment in Samarra, John O'Hara, approx. 190 ADE pages. A story of a man's self destruction over the course of three days.
https://en.wikipedia.org/wiki/Appointment_in_Samarra