When a huge whirlpool blows through Astoria, all of Princess Cascadia's hard work on the Sand Sculpture Festival is destroyed. While the rest of the Royal Mermaid Rescue Crew helps clean up the city, Cascadia is left to try to fix the festival by herself. But then a mysterious helper reveals that there's more damage than Cascadia could have ever imagined. Will Cascadia and her new friend save the day or will she have to wave goodbye to her favorite tradition?

"4"--Spine.