Mine is Franz Kafka's The Castle (1926). The book starts introducing you a man called simply K., who travelled with the mission to work as a surveyor in an also nameless place. But when he arrives, he finds out that the village never really needed his services, yet they got a special job for him, but they never tell him what it's about. Struggling to know the truth, he does a series of infructuous acts to encounter the leaders of the village, who live in a big castle. They are shapeless and slippery. The reader always has a sense the things are going to change, but it's nothing more than a false hope created by the human mind to fill the empty spaces the author left on his track.
Nothing in that book it's real. I mean, not a reality based on social consensus; it's a blurred reality, revealed to K. as the only possession he can have. Some say this novel is a critique to bureaucracy and the illusion of democracy. Maybe it wasn't Kafka's purpose...maybe we'll never know.