The spirit of romance and wanderlust that once drove Petrograd engineer Mstislav Sergeyevich Losj on an interplanetary journey to Mars now carries Taras Zhdanov and Nastya Belaya into one of the invariants of the Metauniverse — in other words, into one of the Branches of the Tree of Time, whose reality parameters match those described in the early 20th century by Alexei Tolstoy in his novel 'Aelita'. The search for the heroes of a beloved book transforms for the young people from a dangerous adventure into a serious investigation. An Artifact discovered on Mars, if not neutralized, could destroy not only the Solar System but the entire Branch. However, there are those who are interested in activating this attribute of the Metagalactic Game. The homeland of Aelita becomes a battlefield for the future of the Children of the Sky.