"You ever hear the one about the cop, the songbird, the psycho and the mafia princess? This twisted tale is told be Harley Quinn herself, as only Harley can tell it. When Gotham's most nefariously narcissistic villain, Roman Sionis (Black Mask), and his zealous right hand, Zsasz, put a target on a young girl named Cass, the city is turned upside down looking for her. While on the trail, Harley clashes with the Birds of Prey, but the unlikely foursome may have to team up to take Roman down."