

One summer, a mermaid named Isla goes swimming with her friends, the Gemstone Dolphins. The youngest dolphin, Emerald, is captured by fishermen. As the dolphins get separated, their distinctive markings disappear. Emerald is put in captivity in a marine research facility on an island. Ken is doing a marine biology internship at the facility, so Barbie and her sisters visit him. Barbie, Ken, Skipper and the puppies use a speedboat to go to the reef. The puppies wait on the boat while Barbie and the others go free diving. Skipper uses her Skipper's camera to take photos of Barbie and Ken exploring the reef. She catches a glimpse of Isla, who is searching for Emerald.

Skipper takes a blurry photo of Isla, and suggests to Barbie and Ken that they follow her. At the resort, Stacie and Chelsea use binoculars and see Emerald at the facility.
