Bottom Liner Blues is a crime novel by the American writer K.C. Constantine set in 1990s Rocksburg, a fictional, blue-collar, Rustbelt town in Western Pennsylvania (modeled on the author's hometown of McKees Rocks, Pennsylvania, adjacent to Pittsburgh). Mario Balzic is the protagonist, an atypical detective for the genre, a Serbo-Italian American cop, middle-aged, unpretentious, a family man who asks questions and uses more sense than force. It is the tenth book in the 17-volume Rocksburg series.