Sergey Ratny - reconstruction engineer from Earth of the XXV century. As a result of a shipwreck, it turns out to be on a planet where the level of technology does not exceed what it was on its home planet at the beginning of the 20th century, although technological development has gone in a slightly different direction... Locals preferred steam over internal combustion engines. Here huge steamboats go to sea, steam cars run on the ground, steam tractors work in the fields, and giant airships dominate the sky. However, here, as once on the home planet, there is a bloody war, and Sergey involuntarily has to become a participant in it. He is mistaken for the construction of the first heavier-than-air vehicles in the history of this planet. After all, only airplanes can withstand the crushing power of enemy airships. The battle for air supremacy begins...