15-year-old Stardust Bellmaine's life is nothing extraordinary. Living in a small town with a Mother who is trying to relive the hippy days and a dynamic best friend called Alex, Stardust faces the everyday tasks of undergoing painful maths lessons and coming face-to-face with snobby drama queens. But one day Stardust's life is turned upside down when she is forced to take on the role of Agent Plasma, an undercover spy with a mission to protect her school's members and reputation. With the arrival of the French exchange students and a plot to ruin her head teacher's notoriety, Stardust is faced with not only trying to hunt down the assassin but carrying on her normal life, too. She has a lot to learn, but will everything go according to plan?