The Lamb by JE Clarkson

When city detective Kate Monroe endures a bitter break up, her only option is to relocate back up north to the town of her birth, Barnsworth. She soon finds that her detecting skills are in demand, as a mysterious serial killer stalks Barnsworth's streets seemingly picking victims at random. Who is this faceless killer and what is the link to "The Four Horseman of the Apocalypse?" Only Kate Monroe and her colleagues can unmask, "The Lamb".