"Garden of Evil" is the twenty fifth episode of the first season of Justice League Action. It is the twenty fifth episode of the series overall.
When Poison Ivy takes control of plant-like Swamp Thing, can the Justice League stop her from using his￼ talents to turn Gotham City into her jungle kingdom?
Gotham City is being overrun by rampant, animated, monstrous vegetation. Vixen leaps through the undergrowth attempting to cut it back but it grows faster than ever. She radios Batman requesting his help, but he replies that he is busy working on an antidote (but doesn't say for what) and will send backup. Soon Superman's heat vision starts to burn through the vegetation to the relief of Vixen and he speculates that Poison Ivy is the likely cause of all this. However, no sooner has Superman arrived than he is gripped by powerful tendrils that he is unable to break free from. They are seen to belong to Swamp Thing who emerges from nearby water. He/it confirms that Poison Ivy is to blame but when he is asked to desist, comes under mind control and continues to attack Superman and Vixen.
Then Firestorm flys overhead and, while chat-ily asking about a blind date he knows Swamp Thing had had, the latter reveals that it was a trick by Poison Ivy who is able to control plants like him. As he is saying that she has to be stopped, he again comes under mind control and we see that it is Poison Ivy who is the controller. She declares that the two together will rule Gotham City. Swamp Thing then attacks Firestorm who flys off before the tendrils can grip him. The Professor then suggests that Firestorm should use nuclear fire to surround Swamp Thing and dry him out. Firestorm tries this and Swamp Thing collapses which enables Superman to break free.
At this time, Poison Ivy makes a televised broadcast to the citizens of Gotham telling them that she and her husband will reprogram the city's biology to make a new Garden of Eden for her to rule over. We then see her best friend, Harley Quinn, running around the city and throwing gas bombs that transform the plants into monstrous mutants. Harley goes to get more bombs from Poison and she is told to bring back her husband-to-be (evidently Swamp Thing) for his wedding. Elsewhere, Batman is gazing at a screen with a map and speaks to Superman telling him he has traced Poison Ivy to a specific building, and Superman sends Vixen on ahead to the place. She sees Harley Quinn leaving with more bombs and follows, knocking her over. Harley throws a bomb which transforms a plant into a monster that grips Vixen tightly. Then Harley sees Swamp Thing being roasted by Firestorm and knocks down the latter with a bowling ball before throwing a bomb that changes Swamp Thing into an even more monstrous verson of himself. Firestorm is hit away but Harley Quinn reminds Swamp Thing of his wedding and he, under mind control, leaves. Vixen breaks free and chases Harley and they end up at the zoo where Harley seems to keep pet hyenas. Vixen chases them back into their cage along with Harley and later hands her over to the police.
Firestorm radios Batman who is speeding through the streets in the Batmobile and asks him about the formula (what formula?). Batman replies that he only has one sample to use and needs to find Poison Ivy. The Batmobile is gripped by vegetation and Firestorm has to free Batman from the vehicle. As Batman goes off to use his formula, Firestorm transforms the Batmobile into a giant hedge trimmer and flys it through the vegetation to shred it. As Poison Ivy plans her wedding arrangements, Superman appears and moves to take her captive, but Swamp Thing springs up from the undergrowth to grip Superman. There follows an extensive fight between the two but Superman is subdued. Batman enters but is caught in the plants and drops the formula. Finally, when Firestorm appears in the customised Batmobile, a tussle with Swamp Thing causes the formula to fly into the air where Superman hits it with heat vision so that the contents empty over Poison Ivy. With her ability to control plants blocked, Swamp Thing is released from her direction and Gotham City gradually returns to normal.
Appearing in “Garden of Evil“