Seaside Sanctuary is supposed to be a safe place for marine animals, but suddenly dolphins are getting sick - and no-one can explain why. Since Elsa Roth spends all of her time at the sanctuary (a perk of her parents' jobs there) she's familiar with all the animals. Elsa is especially worried about Star, a young dolphin she bonded with after seeing him in his wild pen. When the crisis intensifies, it's up to Elsa to solve the mystery before it's too late for Star and the rest of the dolphins.