»The Westing Game

One of my very favourite books, a delightful puzzle by Ellen Raskin, is The Westing Game. A few years ago, while poring through the stacks at a second-hand bookshop in Fairfax or thereabouts, I found an autographed first edition of the book, and picked it up to re-read it.
It's a complex, thrilling book, which picks up the pace and then pauses to let juicy details emerge, and then speeds up again. The writing is rich but never too complex, and has all the non-politically-correct sorts of details that could never appear in a so-called children's book today.
The Wikipedia entry on Ellen Raskin has some great pointers to other internet resources; the entry for the book itself has most of the plot detail, but is useful after-the-fact. The University of Wisconsin has a few manuscript pages online.