Diego and Alicia are exploring the ocean in the Rescue Center Submarine when they hear a cry for help. Using Click, the duo find a mystery fish named Lucy who has lost her way. In order to bring her back home, Diego and Alicia must determine what kind of fish Lucy is by finding clues. They discover Lucy has 3,000 teeth, skin with spots and stripes and a tail she wiggles from side to side. What could she be? A Whale Shark!