A man, a monkey and the insidious influence of green tea. If you've never read Green Tea, a short story by Joseph Sheridan Le Fanu, a renowned Irish writer of supernatural tales, then maybe it's about time to rectify that matter.
Check it out at Project Gutenberg. It's paired with another Le Fanu story, Mr. Justice Harbottle, which is also worth your time. Now that you mention it, there are plenty of Le Fanu tales that are worth your time, but this is as good a place as any to start.