A strange green stone, which bears the name “Serpentine of Tarkhankut,” was given to eleven-year-old Rostik quite by accident under very mysterious circumstances in order to guide its new owner through the corridor of shadows to the world of the Twelve Cities. There Rostik will have to learn about the magical Order of the Twelve Stones, meet its guards, walk with them a path full of dangers from sunny Gelion to the cursed Fatalunia, and finally prove to everyone and to himself that he is the very twelfth guard that the Order has been waiting for. a very long time ago...