Harley Quinn and Poison Ivy escape from Arkham Asylum and head back to Ivy's hideout; however, Harley proves to be a demanding roommate, so Ivy helps her take over a carnival and even grows her plant versions of Batman and Robin to boss around--but when Poison Ivy feels she has done enough and withdraws from the field, Harley discovers that being a criminal boss is a lot more difficult than she imagined.