At the start of the story, she is a woman who works at the office of Doctor Comstock in a small town in Ohio. One day, within this same city a mysterious gas is released in a nearby school, which caused all of the students to become aroused and participate in a giant orgy; one that they do not remember having, once they come to their senses. One student, however, a girl named Fanny Keyes, arrives at school too late to breathe in the gas, and therefore, is the only one who retains memory of the incident.Upon learning of her outcry of the event, the scientist suggests that they kill Fanny, but Comstock feels it would be more risk-adverse to "diagnose" her with a rare mental illness. Once in the doctor's care, the two reveal to Fanny that they are actually interplanetary invaders from a solar system named "Sirius", which was destroyed some time ago during a catastrophe. The continue to divulge that they plan to use the orgy gas, dubbed "Erossina", to make the human population of Earth their slaves, but the gas isn't quite at the desired level.
They decide to use Fanny as a guinea pig to perfect the formula, and study her as she is sexually violated by Shwoll, a gorilla-like animal specimen from their planet which they were able to bring along with them. After the interspecies mating, the female scientist attempts to murder Fanny by raping her to death with a large rod, but is stopped when Fanny's brother, Billy, comes to rescue her. During the struggle, a tank containing the Erossina is struck, causing the leaking chemical to affect, everyone in the room, including Shwoll, who proceeds to grab the scientist and rape her. She does not survive.