It doesn't matter how old the case is, when the dog finds a rusty revolver in the back yard, sean investigates.  He finds a bag of swag, what was once a large stash of cash, some of it from the beginning of the 20th century.

Next thing Sean knows, some low-life attacks him with a length of gas pipe. Then a double murder, then there are cops from multiple jurisdictions galloping about.  Shades of the 1930's!  Ultimately the tracks lead the pint-sized detective to corruption, payoffs and answers to questions nearly one hundred years old.