While the girls are battling an alien creature named Starro the Conqueror, Batgirl learns that Harleen Quinzel is moving to Metropolis from Gotham City. The other five find Harleen's pranks and behavior to be insufferably annoying, but struggle to put up with her for their friend's sake. Barbara finally learns their opinions by using Diana's Lasso of Truth on them and storms away, ready to give up on their friendship. Meanwhile, Harleen befriends Selina Kyle, Pamela Isley, Carol Ferris, Doris Zeul, and Leslie Willis and the six prepare for a spree of vandalism. Barbara is disappointed that Harleen wants to hang out with them instead of her; after she leaves, the six assume their villain identities (with Selina becoming Catwoman) and begin committing crimes all over Metropolis. The other five girls rush to stop them, but Harley Quinn's antics distract them so the villains can gain the upper hand. A talk with Barry Allen at the Sweet Justice ice cream shop makes Barbara realize that she and Harleen can have separate circles of friends and still remain on good terms with each other. She calls Harley to explain the situation, distracting her long enough for Barbara to suit up as Batgirl and join the fight. The villains flee the scene as the police arrive, and the six heroes apologize to one another and promise to stick together against these threats. Later, Barbara and Harleen notice each other's fresh injuries (sustained in the fight), but quickly dismiss their suspicions in favor of hanging out at a comic shop.