When Mia and Liam step through the Wonder Doorway, they find themselves in a shimmering underwater world where they reunite with their friend Zoe. Guided by a glowing seashell, the three friends are led to the gates of the Underwater Kingdom, a place filled with coral palaces, schools of sparkling fish, and talking sea creatures.Together, they discover that courage, teamwork, and friendship can restore light to even the darkest depths.