Doctor Poison first appeared as the chief of the poison division for a Nazi spy band who had planned to contaminate the United States Army's water with "Reverso," a drug that compels whoever takes it to "do the exact opposite of what they are told." She disguised her sex by wearing a bulky hooded costume and a mask. Doctor Poison's underlings captured Steve Trevor and brought him to their base in America where he was questioned by Doctor Poison. Wonder Woman, disguised as a nurse, aided Steve Trevor but was forced to flee the scene after a lengthy battle. Meanwhile, the Reverso drug was successful in turning thousands of American soldiers against their superiors. Wonder Woman recruited Etta Candy to help her create a diversion for Doctor Poison's troops, which led to the defeat of the villain. When Wonder Woman pulled her disguise off, she discovered Doctor Poison to be Maru, a Japanese princess. Maru made one more attempt to defeat the amazon, but was tackled by Etta Candy and coerced into giving up the antidote. She was later taken into police custody.