And Then There Were None by Agatha Christie

Ten strangers are invited to an exclusive island by a mysterious U.N. Owen. One by one the guests start dying just as a certain poem predicts. This U.N. Owen knows all there secrets and is using it against them. The smallest mistake can lead to death. The pasts that the guests are desperately trying to forget seem to be following them everywhere they go. All the remaining guests are starting to panic, which one of them is going to die next and which one has any information about the twisted millionaire?
The plot is incredibly well thought-out. In most mystery novels, the suspect is relatively obvious but definitely not in this one. I was left guessing until the very last second. Unlike most mysteries, the story wraps up well and leaves no questions and loose strings. The ending was heart-stoppingly suspenseful. My favorite part of this novel was the setting. The island provided an excellently scary and suspenseful environment to match the plot.
The characters were each unique but were all connected in the sense that they all committed murder that was untouched by the law. All ten characters were clearly well-thought-out and had interesting backstories that were just as well-planned as the rest of this story. All of the characters could have been the murderer. Although all characters were deep and were constantly changing, the most mysterious one was U.N. Owen. After it was revealed that his name was a play on the word "unknown", I grew extremely excited about finding out who he was.