What is the main conflict in Batman: The Long Halloween by Jeph Loeb?

The conflict involves the efforts of Batman, district attorney Harvey Dent, and Gotham City Chief of Police Jim Gordon to take down the mafia boss Carmine "The Roman" Falcone. As the story progresses, a mysterious serial killer referred to as Holiday begins killing members of Falcone's family and gang. In the end, the pursuit of Falcone drives Dent to break the law and transform himself into the villain Two-Face.