Good writing. You can feel it from the beginning that you're in for a treat. Yes, they do catch the culprit. But it's not typical lighthearted good-guy / bad-guy fare. The characters are complex. They resolve problems and escape the prisons they've built for themselves as a result of Clinton's (played perfectly by Fran Kranz) dogged insistence on finding the killer of his cat.
The subtext of the story is what stays with you and makes you think about life. Clinton is portrayed as an insecure momma's boy, unable to support himself, spending his days creating little figurines and trying to sell them from his mother's front lawn. Your first impression is that he's a pathetic, harmless loser doomed to a life of obscure mediocrity. There is nothing to indicate otherwise, until someone shoots his aging cat with a crossbow, leaving the poor animal to drag itself to Clinton's house and finally die there. Clinton's sadness is off the charts. His only friend in the world is mercilessly shot down and left to die alone. Instead of simply moving on with life, Clinton transforms into a relentless crusader, pestering and bullying anyone who won't help him locate the killer of his cat.
Clinton's probing reveals sordid secrets of almost everyone he investigates. Every attempt to stop him fails. His sometime ally is Greta (played by Nikki Reed) who "co-owned" the cat. Even she drops out of the investigation when her secrets are revealed. But nothing will stop Clinton. As he knocks down and reveals each character's personal tragedy, he does what you don't expect: he shows true compassion for them. Clinton the oddball is the only character true to himself and his convictions. His human authenticity is a transformative power that forces his antagonists to let down their facades and become human again.
You'll laugh, you'll cry and you'll feel something profound. See this movie.