Heart of Darkness In Joseph Conrad's book Heart of Darkness the Europeans are cut off from civilization, overtaken by greed, exploitation, and material interests from his own kind. Conrad develops themes of personal power, individual responsibility, and social justice. His book has all the trappings of the conventional adventure tale - mystery, exotic setting, escape, suspense, unexpected attack. The book is a record of things seen and done by Conrad while in the Belgian Congo. Conrad uses Marlow, the main character in the book, as a narrator so he himself can enter the story and tell it out of his own philosophical mind.