"The Adventure of English: The biography of a language" by Melvyn Bragg. Non-fiction is a departure for me but I've always been interested in the evolution of the English language, more so since marrying an Englishman.
Seriously ... this book is SO fascinating and I recommend listening to it (as I am) as oppsed to reading it. The narration is perfect as you hear the difference between "path" and "path".