The Murders in the Rue Morgue is the story of C. Auguste Dupin, a detective investigating the brutal murder of two women in the titular neighborhood. After pursuing a series of bizarre leads, Dupin discovers that the murderer is in fact an escaped orangutan, property of a negligent and brutal sailor. Terrified and confused in the London cityscape, the beast ran amok and killed. The story is often referred to as the first example of detective fiction.
Boasting the largest collection of book summaries, BookRags is the best option for titles you can't find elsewhere. They offer all of the basics (quotes, chapter summary, characters, historical context, literary criticism) but also walk through a few major topics that recur throughout the book, which can be particularly useful for essay writing.
If you're bored by traditional book notes, try Shmoop! They write their summaries in an approachable, entertaining style. Their comprehensive offering includes chapter by chapter summaries, themes, quotes, character analysis, study quizzes, and even flash cards and infographics.