A snafu by Harley sends Poison Ivy back to Arkham, and Ivy swears off working with Harley forever. But Harley won't take no for an answer, so when Ivy breaks out and heads to South America, Harley's right behind her. Oily politicians, cutthroat mercenaries, and shower scenes abound.
Harley and Ivy are scaling a building to steal a very rare plant known as the zombie root. Ivy wants this plat to turn everyone in Gotham into willing slaves. When they get into the building and get to the plant the lights are turned on by a group of Gotham's elite. Ivy shoots some thorns grabs the plant and both Ivy and Harley exit the way they came in. Harley screwed up and thought the Botanical Society Party was tomorrow. As they scale down the building Harley reassures her that none of these hoity-toity types have the guts to fallow them. Unfortunately Bruce Wayne a.k.a. Batman is one of those hoity-toity guests. He quickly changes and cuts the vine the girls were climbing on, dropping them to the ledge. Batman them makes his move to stop the girls. They fight and in a panic Harley tosses the plant at Batman's head. This enrages Ivy who attacks Harley allowing Batman to capture both of them.
At the asylum Harley tries to cheer up Ivy. Ivy can only think of ways to kill Harley. In the showers Harley continues to try and cheer Ivy up. She even gives her a playful snap on the butt with a towel. Ivy snaps and attacks Harley and starts banging her head on the floor.
Harley and Ivy are placed into their cells that are across the hall from each other. The front of their cells are not bars but a clear window. Harley taps on her cell to get Ivy's attention. She then holds up a sign that says I'm Sorry XOXXO. Ivy looks at her and cut the bud off the top of a rose she has in her cell. Ivy then plans her escape by cutting her thumb and dropping her blood in the flower pot. She then calls to a guard screaming about her cut hand. When the guard walks in she is attacked but Ivy's mutant rose plant. She grabs the guards gun and takes off down the leaving a confused Harley locked in her cell. Ivy goes a short way down the hall and kisses a guard who become brainwashed and lets her go. As the brainwashed guard walks down the hall Harley asks the guard to let her out and he does. Harley makes her escape by kissing male guards and attacking them with plants.
The next day Ivy is on a cruse liner leaving for South America to find the Zombie Root. As the Ship leaves Harley shows up waving for Ivy to let her on the ship. Ivy justs turns her back on Harley. Harley stands on the pier and starts to cry as she realizes Ivy is not going to let her come with her. As she turn to walk away she is roped by one of the Ship's life preservers. The story ends with Harley trying to get Ivy to let her into the ship instead of just floating behind it.