Review of The Pledge

I saw this when it was first released in the theatres and I've since watched it numerous times on TV but, even though I know it's based on a crime novel (Sight and Sound), the beginning and ending scenes still leave you wondering: did Jerry Black, failing to catch his last killer, retire into the life of a doddering drunk who is fantasizing about the movie's events, or was he numbing the pain of losing his idyllic small-town life by using his girlfriend's daughter as bait to catch the serial killer?