Batman: Legends of the Dark Knight #42 (1993)

While attending a charity event at Gotham University, Bruce Wayne spots university regent Ian Spencer attempting to commit suicide. Bruce changes into Batman and tries to save Spencer, but fails. Shortly after, he sees a familiar face in the crowd of rubberneckers: the recently-paroled Pamela Isley, now working at the university under a science grant approved by Spencer. Recalling Isley's obsession with him and Spencer's delusional mutterings about a woman, Batman suspects that Isley is back to her old tricks as Poison Ivy. Batman visits Isley's new greenhouse, where a hurt Isley tells him that she has been completely rehabilitated of both her insanity and her hypnotic pheromones. Batman then travels to Ian Spencer's home, where he finds several vials of a strange drug inside Spencer's secret safe. Batman spends most of the night analyzing the drug, all while fighting his strange new obsession with Isley. The analysis is interrupted by Isley herself, who uses the Bat-Signal to summon Batman to police headquarters. There, Isley explains to Batman that she had accidentally created the drug - dubbed "Edenspring" - while working under Spencer. Spencer, indebted to criminals and realizing Edenspring's value as a recreational drug, had shared its secret with art dealer and crime boss Dominique Alioso, who in turn has been forcing Isley to make more and more of the drug. It was Dominique, Isley fears, who had killed Spencer. Determined to prove Isley's innocence, Batman hunts down Dominique and her bodyguard Victor and sends them to the police for the murder of Ian Spencer and the marketing an untested drug. Afterwards, he joyfully phones Isley, thinking the case closed. But in truth, Isley has been concocting schemes of her own all along.