"He delves into the town's criminal underbelly"
What does that even mean? Unless you are a criminal to start with, how are you going to delve into the criminal underbelly of a town, and how would you know how to delve into it?
Perhaps he's just standing in line at the local Gregg's (which the real life Gerard Butler is a HUGE fan of - loves slipping a greasy sausage roll down his throat) and overhears a conversation from a couple of underworld types, standing in line for steak bakes.
Currently in the midst of another boring day in the office, everyman Butler offers them his services in dealing with whatever problem he overhead them discussing.
Next thing you know, Butler is delving into the town's criminal underbelly...