In Barbie Rainbow Fairy Mermaid Princess, Alina, played by Barbie, must give up her beautiful wings and transform into a mermaid in order to save her friend, Nalu, the mermaid prince. The evil sorceress Luvina has kidnapped Nalu, the mermaid prince, and wants to borrow him to get the Immunity Berry and henceforth rule over Fantasy Wonderland and the mermaid kingdom. Only Alina can stop this, but his own strength is not enough, she must ask for the help of the mermaid Loli. Lori is a mermaid who doesn't trust others, but Alina impresses her with her sincerity. A much tougher challenge awaits Alina. To save Nalu, Alina will have to give up her wings. Can Alina do it? If she fails, Dream Fairyland and the Mermaid Kingdom will be in Luvina's hands forever.