Translate the text into English. Archaeologist Elis Tanner is busy with excavations in the south of France, trying to uncover, in the underground labyrinths of Carcassonne, the mystery surrounding the disappearance of the Cathars, who, according to legend, were guardians of the Holy Grail. Parallel events unfold in the 13th century — a young woman Alais tries to understand the symbols and diagrams of the three sacred books entrusted to her, and to save her life.