The story begins in the Soviet Union, just after the end of the Russian Civil War. An engineer Mstislav Sergeyevich Los', designs and constructs a revolutionary pulse detonation rocket and decides to set course for Mars. Looking for a companion for the travel, he finally leaves Earth with a retired soldier, Alexei Gusev. Arriving on Mars, they discover that the planet is inhabited by an advanced civilization. However, the gap between the ruling class and the workers is very strong and reminiscent of early capitalism, with workers living in underground corridors near their machines. Later in the novel, it is explained that Martians are descendants of both local races and of Atlanteans who came there after the sinking of their home continent (here Tolstoy was inspired by Helena Blavatsky's books). Mars is now ruled by Engineers but all is not well. While speaking before an assembly, their leader, Toscoob, says that the city must be destroyed to ease the fall of Mars. Aelita, Toscoob's beautiful daughter and the princess of Mars, later reveals to Los' that the planet is dying, that the polar ice caps are not melting as they once did and the planet is facing an environmental catastrophe...