I'm not even sure how to describe this book. It is set in an apparently familiar place - 1980s England - but this is an alternate universe in which the Crimean War is still going on after 175 years, time travel by government agents called Chronoguards is commonplace, and people can not only travel to and live in books but can interact with characters who, like actors in a play, lead independent lives within their books in between the scenes in which they appear.
The heroine, Thursday Next, is a "Spec Ops" agent who specializes in literary crimes. As a Literatech, she spends much of her time on cases involving things like bogus copies of lost Shakespeare plays. But when someone starts kidnapping literary characters and murdering them, culminating in the theft of the manuscript of Jane Eyre and the kidnap of its heroine, Thursday is confronted with a much greater challenge. She must subdue the arch-villain Acheron Hades and return Jane to her book.
I've now actually read three books in this series (or should I say listened to them as they are read by the very capable Elizabeth Sastro) and I have really enjoyed Fforde's inventiveness and sense of humor, as well as his knack for creating characters that are entertaining and sympathetic. The books abound with literary allusions, so the English majors out there would get a special enjoyment from reading them, but anyone who likes alternate universe fantasy, satirical humor, or books with a literary twist should check out the Eyre Affair and other works by Jasper Fforde. Just as an aside, I learned about Fforde from a read-alike list for Terry Pratchett, so if you enjoy his books you should also try these.