#42, The Maltese Falcon, by Dashiell Hammett

The movie is entirely faithful to this book.  I found the book, though, to be a little easier to follow.  I kept picturing Humphrey Bogart, Sidney Greenstreet, Peter Lorre, and all the rest as I read--Sam Spade is a good old-fashioned hard-boiled detective.  No whining about how hard his life has been, no 12-step programs, no social commentary, just a great story.  Truly a classic.