The heroes of the book are heading to Mars, where, as they thought, their leader and creator of the spaceship, Komov, died. However, at the same time, a spaceship arrived on Mars with a representative of a “competing company” - the United States. The astronaut landed at night, hastening to establish the priority of the United States in the exploration of Mars. The next two books tell about the adventures of the heroes on the “sister of the earth” - Venus, where they discover intelligent inhabitants and the legacy of the ancient civilization of the lost ancient planet, the legendary Phaeton, who foresaw the appearance of earthlings.