Perfidia is a historical romance and crime fiction novel by American author James Ellroy. Published in 2014, it is the first novel in the second L.A. Quartet, referring to his four prior novels from the first L.A. Quartet. Perfidia was released September 9, 2014. A Waterstones exclusive limited edition of Perfidia was released September 11, 2014, and includes an essay by Ellroy himself titled "Ellroy's History – Then and Now." The title, Perfidia, is Italian for the word perfidy, (see also perfidia) and is also the name of the big band song, Perfidia.