The story is about ocean corals which suddenly turns gray, a young biologist named Marina who was the first one to notice the changes and along with her research partner an elderly scientist goes on an adventure to the ocean to find out about the coral turning gray. There they find three more friends a silver-gray dolphin with crescent mark, an ancient sea turtle with golden patterns and a purple octopus with orange spots. The story is full of adventure and fun and perfect for kids 5 to 12 years.