This is a very handy book if you're a fan of Agatha Christie like I am. All the characters in her books are listed with mini-bios. It's not in depth, but it did get me back to reading Christie after a lapse of some years. I recommend caution, though, because it does give away the solutions to several mysteries. I subtracted a star because of that. As far as I know, this book is out of print, but you can find it easily enough on eBay (like I did). I also recommend "The Bedside, Bathtub & Armchair Companion to Agatha Christie" by Dick Riley and Pam McAllister.