Mystery-lover Libby is excited but nervous when she's sent to live with her aunt while her mother is working abroad. For Aunt Agatha is the headmistress of an extraordinary travelling school that moves from country to country around the world. Joining the school in Paris, Libby is just starting to find her feet when Agatha is arrested, accused of a daring jewel robbery! Can Libby and her new best friend Connie find the real thief and save her aunt?