John Cooper knows that for cops there is no such thing as good luck, only bad luck. If you got there in time to stop the robbery you were doing your job. If you got there too late, well, them's the breaks, and wasn't that bad luck all around.
Spot the guy acting twitchy, pull him over and when you run his plates you find out they're stolen so you cuff him and one more dirtbag's off the streets. Come across the same car and the same dirtbag after he's taken the car for a joyride and crashed into a minivan full of kids? Bad luck.
If you convince the battered girlfriend to make a complaint you've proven yourself to be trustworthy, one of those good cops that can really make a difference in someone's life. If you can't? Well, there's that bad luck going for you again.
But, despite all that bad luck, when you make it through the day and you and your partner walk through the parking lot on your way home, and he turns, laughing at something you said and smiles that smile that's just for you? Cooper starts to wonder if maybe there's such a thing as good luck, after all.