I recently finished reading Crime and Punishment by F.M Dostoevsky. Without no doubt is one of the most psychological books I have read until now. The subject it tackles, respectively a poor man who commits a crime and before being punished by the law, he is punished by his own guilt and conscience is one rather common, however, the details is what makes this book so captivating.
Dostoevsky brings to the front moral subjects that are still common to the modern man. The novel, with all those details into the mind of the protagonist, Rodion Raskolnikov, makes the reader think and be one with the character himself.
I recommend this book if you want to have your conscience wonder.