When Barbie's sister Chelsea thinks her birthday has been skipped, she hunts for a magic gem on a jungle island that will grant her wish to get it back.

At a summer performing arts program in New York City, Barbie from Malibu meets Barbie from Brooklyn, and the two become fast friends.

Brooklyn Barbie and Malibu Barbie — plus Skipper, Stacie and Chelsea — transform into mermaids to help save Pacifica in this underwater adventure.