Perfidia is a historical romance[1] and crime fiction novel by American author James Ellroy.

[4][5] The main characters are Hideo Ashida, a Japanese Los Angeles Police Department (LAPD) chemist, Kay Lake, a young woman looking for adventure, the real life William H. Parker, a gifted LAPD captain with a drinking problem, and Dudley Smith, an LAPD sergeant born in Dublin, Ireland, and raised in Los Angeles.

The first chapter introduces the reader to Hideo Ashida, on Saturday, December 6, 1941, at 9:08 am.

Characters appearing in previous Ellroy novels include Ward Littell, Scottie Bennett, Claire de Haven, Mike Bruening, Dick Carlisle, Dot Rothstein, Buzz Meeks, Lee Blanchard, Bucky Bleichert and Saul Lesnik.

Perfidia was on The New York Times Best Sellers list for hardcover fiction at number 16 on September 28, 2014.