Highly Low is based on when forensic accountant Leo Massey faces foreclosure on his home, a desperate night at an old boxing gym leads him into Pittsburgh's underground fighting scene. There he meets Vinnie "The Veal" Scaletta, a sweet-natured but dim boxer, and his fierce sister Mia. Using his number-crunching skills, Leo uncovers a money-skimming scheme targeting Vinnie, pitting them against a mob-connected manager.