Batman and Nightwing discover that Poison Ivy and Floronic Man (Jason Woodrue) have teamed up. Much to their reluctance, they decide to look for Harley Quinn (Ivy’s best friend and Joker’s usual sidekick), to find out where the duo are hiding; however, Harley has gone off the grid since getting paroled. Batman leaves finding Harley to Nightwing, while he gets information from A.R.G.U.S.
At A.R.G.U.S. HQ, Batman learns that Ivy and Woodrue stole the information on Swamp Thing’s birth and kidnapped a scientist named Dr. Harold Goldbloom who could help them replicate the process and turn everyone into plant people.
Nightwing finds Harley working as a waitress at a restaurant. Tailing her, Nightwing angers her since she wants to live a normal life, but her past as a super criminal keeps her from getting hired as a psychiatrist. Eventually, the two have an intimate moment with each other with the result being Harley is convinced to help. Batman walks in on the two.
Harley leads them to a popular hangout for henchmen where she gets the location of Ivy from one of her old minions named Shrubby. The trio head to Blüdhaven where Ivy is saddened to see her friend helping Batman. Woodrue fatally wounds Dr. Goldbloom to keep him quiet as he and Ivy escape as their lab catches fire. However, the dying Dr. Goldbloom reveals that the duo are heading to Slaughter Swamp in Louisiana where the correct swamp chemicals are.