Anyone who has been interested in the theory of relativity knows the twin paradox. An astronaut can fly a huge distance in a couple of years, but when he returns home, centuries will have passed, all his relatives will die, and the world will change beyond recognition. This is how speed affects time. How does acceleration affect it? Starship Valentin Petrov has his own thoughts on this matter. And there is something to risk himself for - after all, his relatives are waiting for him at home, who no longer hope to see him again. The story consists of three parts that describe incredible events on behalf of their three participants.