The world that survived the nuclear war. Residents of the Soviet Union live in bomb shelters. The largest of them is near the city of Pobedograd and it goes down a hundred floors... Fifth grader Mitka lives in an underground city all his life, takes the subway to the Palace of Pioneers, goes to school and dreams of seeing the world on the surface. But upstairs, where nuclear summer radiation has descended on the world, you can't live. And in the subway tunnels there are ghosts and terrible droughts that drag careless diggers into the darkness. And a mysterious ghost train runs through the tunnels... But in the depths of the bomb shelter there was a new threat that could destroy all its inhabitants