The main character is a professional time traveler. After undergoing a rigorous selection process and an intensive training course, he enters the Horizon program, which involves confirming in practice the theory of the plurality of worlds or, in other words, the existence of parallel universes. To do this, he needs to move three times to the same place and time, and he must go there from the present with a difference of only one minute. He gets the farthest event horizon - 2050. In his first attempt, everything goes smoothly, but the second turns out in such a way that there may not be a third...