Little Dolphin and his friends in Urchin Bay always have fun and adventures together, in their underwater world. Poppy the spinner dolphin is in a flap! It's her birthday, and no one seems to have remembered. But Little Dolphin and Milo have a secret, they're planning her a surprise party! But on the day of the celebration, Poppy goes off in a sulk — can Little Dolphin find her before her day is ruined?