The Adventures of Sherlock Holmes follow the titular detective and his partner, surgeon and amateur investigator Dr. John Watson, as they solve crimes and plumb the nature of human thought in Victorian London. Holmes is an aesthete and a logician, a student of deductive reasoning who sometimes grows frustrated with the illogical world around him, retreating into art or fixation on a case. Watson is his foil, a collected and charming man who grounds his friend and partner in the real world.
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.