A detective story is and remains a detective story, like it or not.
This one, however, does take the pains to circumvent a couple of the usual easy ways out, starting with the self-destructive policeman (Yes! He's gone! Replaced with a merry pair of youngsters!) and ending with the non-solution of half of the mystery.
Frustrating, in a way, yet refreshing!
(A minus, though, for the blond young girl as the victim. Been there, done that.)