Undergods (2021) on Netflix

Plot summary

Z and K are vagrants who scavenge corpses in a post-apocalyptic suburb. While driving their van, they talk about disturbing dreams they have had. Z describes one that recurs, about a room containing a ghost. That dream opens another story, set in the modern day, about Ron and Ruth, a middle-aged couple who are the only people living in a new apartment building. One night a man named Harry knocks at their door. He says he lives elsewhere in the building and cannot get into his own place. Ron invites him in and offers hospitality.