Do Androids Dream of Electric Sheep? is set on a dying, post-war Earth from which most people have already emigrated. Rick Deckard, a bounty hunter, is assigned to hunt down six escaped androids, who are all the latest model and nearly impossible to detect. The only way to tell a human from an android is to administer an empathy test; empathy is highly valued as the only characteristic separating man from machine. As Deckard finds and brutally destroys the "andys," he is faced with uncomfortable questions about his own humanity.
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.
You won't get any frills with GradeSaver -- just the content you expect. Their study guides include a full plot summary, themes and character analysis, study questions, and the e-text of the book. One hidden gem is their collection of literature essays, but you'll have to pay for it.