The Moving Finger  
Agatha Christie
HarperCollins
Lymstock is a town with more than its share of shameful secrets—a town where even a sudden outbreak of anonymous hate mail causes only a minor stir.  But all that changes when one of the recipients, Mrs. Symmington, commits suicide. Her final note says “I can’t go on,” but Miss Marple questions the coroner’s verdict of suicide. Soon nobody is sure of anyone—as secrets stop being shameful and start becoming deadly.