Who can assume that a charming young lady is an experienced detective? After all, at first glance, high school student Daria Bestuzheva gives the impression of a very ordinary girl: she goes to lessons, keeps secrets with her classmates, writes letters to a distant friend in Tomsk... Few of her new acquaintances know that Dasha is not into music, but into fencing and her hobby is solving detective stories puzzles! Only this time she found truly dangerous opponents. While investigating a mysterious double murder, Dasha came across the activities of several secret societies at once. Their members are accustomed to protecting their secrets at all costs...