Should a man build his own dungeon?

The main character of the film writes a diary. For over 20 years he has lived in a bunker and has not ventured outside. His only companions are ghosts of the past. He tries to find an explanation for the fateful course of events, which has destroyed the whole earth. The feeling of guilt does not leave him, as he believes that he could have prevented the apocalypse and the death of his beloved.