Mystery-lover Libby is excited but nervous when she’s sent to live with her aunt while her mother is working abroad. Her Aunt Agatha is the headmistress of an extraordinary travelling school that moves from country to country. Libby joins the school in Paris, where she 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?