A Great Deliverance - by Elizabeth George

Two police detectives from Scottland Yard get sent to a small English town to solve a horrible murder.  While there they end up discovering just how sick some people can be.  This family is so far past disfunctional that they can't even see it in the rear view mirror.  Yes I did just say that.  I loved this book though so much I got the movie from the library yes it was made into a pbs movie and I will be watching it this weekend.