Marnie is having so much fun at Minibeast Academy, a school for bugs tucked into a giant tree at the bottom of the museum gardens. And this term it's time for something really exciting – the Great Critter Contest! The contest sees minibug students set off to explore the school in teams, searching for clues. The winners get an incredible prize and Marnie and her team – best friends Floyd the bee (who is really an A) and Star the super-strong princess ant – are determined to be first to cross the finish line. But when Veronica gets into trouble and needs rescuing, Marnie and her team have to decide whether winning really is the most important thing.