"Трианон" is the second book of series of "Зерцалия". A main heroine Катерине and her friends again had to run into natives from the the world behind the looking-glass world. Now доппельгангерам is needed she, more faithful, her blood, at any time to pass through mirrors. In turn, clubmen Калиостро too search possibility of passing to Зерцалию: they try to recover Трианон, magic artefact known yet from times of Калиостро, and also to recreate a mirror machine. Reading the diaries of the disappearing father, Катерина hears not only about falling to his lot mishaps in Зерцалии but also about existence of the secret related to her birth. To know a true, meet with a mother and save a остекленевшего darling, a girl decides to be carried in Зерцалию. But she not alone. The frightful whirlwind caused by demonic forces carries away there her friends. Here they are waited by new adventures and tests.