Wedding bells are ringing after the Debutante Ball when Darla comes home early from Paris to her daughter, nieces, and nephews, and announces that she is finally going to marry Urchin. This will also mean that Darla and Urchin will leave the Plaza Hotel together and raise their daughter without the constant help of Nanny, but will it be able to come true after incoming trouble?

On a hot day in the Plaza Hotel, Eloise's mother stops by for a surprise visit to take Eloise away for the whole summer. During this, Eloise discovers that her mother's family is consisted of mermaids and she even gets to spend time with her long-lost father she never got to grow up with. However, there are two evil ones out for revenge during this peaceful visit.