After being thrown off her Olympic swim team, the so-called Mermaid Queen swore to get revenge. She disguised herself as the mythological King Neptune and used a special potion to mind-control several women into serving as her mermaid minions. They would attack ships with explosives and capture the men aboard as they attempted to escape. Wonder Woman heard from a sailor, Tom Googins, about his experience with the mermaids. Wonder Woman remained skeptical, but Col. Steve Trever agreed to inspect the area where the mermaids supposedly resided. However, he was soon kidnapped by the mermaids and taken prisoner for King Neptune (the Mermaid Queen in disguise), who forced him to drink the Nepenthe.
Wonder Woman soon intervened, along with Etta Candy and the Holliday Girls. Wonder Woman was eventually captured by the mermaids, and ordered by King Neptune to give up any knowledge that will aid her. After refusing, Wonder Woman is forced to drink the Nepenthe, but it has no affect on her. Soon, she is aided by the Holliday Girls, and rescues Steve Trevor. Defeated, the Mermaid Queen reveals her identity to Wonder Woman. She is then taken to Reform Island.