As a young woman, Grendy swam her way to fame in the kitschy underwater pageants of Mermaid Springs, a premier attraction of pre-Disney Florida. When she met her minister husband, North, she hung up her fins and moved with him to the Midwest. Thirty-six years later, a reunion of the Mermaids of Yesteryear brings Grendy and North back to Mermaid City, where they decide to purchase a second home. In no time at all, Grendy lands a starring role in the "Mermaids on the Moon" Labor Day spectacular, and life seems very good indeed. So when Grendy suddenly goes missing, leaving only a cryptic note behind, her daughter, France, goes to Mermaid City to find out what happened.