It's the last day of fourth grade, and Zesty is excited to start summer vacation because she and her best pal, Gulfer, are going to vacation together on Starstruck Island! On this magical island, the sun always shines and the moon never rises. But when Zesty and Gulfer arrive, it begins to rain, and nighttime falls. It's up to Zesty and her crew to get to the bottom of these strange occurrences, solve the mystery of the island, and restore balance to the ocean once more.