A twisted tale told by Harley Quinn herself: When Gotham's most nefariously narcissistic villain Roman Sionis, and his zealous right-hand, Zsasz, put a target on a young girl named Cass, the city is turned upside-down looking for her. Harley, Huntress, Black Canary, and Renee Montoya's paths collide, and the unlikely foursome has no choice but to team up to take down Roman.