The Strange Case of Dr. Jekyll and Mr. Hyde
A short story by Robert Louis Stevenson where a lawyer by the name of Mr. Utterson investigates the circumstances around a Mr. Hyde, who seems to be hated by anyone he comes across, and the crimes he commits.
Without spoiling too much, the ending did not come as a surprise to me, although the way it was written really made me think about analogies to online anonymity in the modern day, and cases like Hunting Warhead in which "internet liberty" is directly harmful.