Is there a puzzle in your story that the main character is trying to solve?

In the Heart of Darkness by Joseph Conrad the main character, Marlow, is trying to solve the puzzle of who is this mysterious Mr. Kurtz.  When Marlow first hears of Mr. Kurtz at the companies headquarters he is interested how this one man can produce more ivory than the rest of the other outposts combined. However as he arrives at the next camp he becomes more and more captivated by Mr. Kurtz and it starts to become an obsession. Marlow is bewildered how Mr. Kurtz turned the canoes with the ivory around or how he is living without anymore white people. It just does not make sense to him and this becomes one of his main motivations as he goes farther down the river. The second chapter only heightens Marlow's obsession as they are attacked for the purpose of keeping Kurtz with them. Marlow now admires this man as many others see Kurtz as a rogue.  However, with all the time Marlow had on the river he builds up Kurtz to be larger than life. In trying to find out who Kurtz is Marlow imagines Kurtz as a savior. The puzzle of who Mr. Kurtz is was solved, but not to the excitement of Marlow. After being shown around the camp by the harlequin Marlow starts to believe that Kurtz has become savage. The skulls on the spears combined with Kurtz's unholy obsession with ivy has tarnished Marlow's opinion of him. This resentment is seemingly abandoned shortly after when a Marlow allies with Kurtz instead of the manager. I believe Marlow did this because he was still obsessed with the character of Kurtz, and in trying to find out Kurtz was he built a false pretense of who Kurtz actually was. Marlow never solved the puzzle of who Kurtz was, but instead used the image he had created for Kurtz on the way to his camp.