There is a show on Netflix called Katla that I just binged this weekend, and it was great. It's set in Iceland and deals with the impending eruption of a volcano by the same name. Set in a rural part of the country, the nearest small town has been mostly evacuated. A few of the locals as well as some scientific folks are staying around to keep an eye on things. It's a bleak setting to say the least. One day, at the scientific station on a glacier near the volcano, a naked woman covered in ash and mud comes walking down the glacier. She is taken to a small clinic in the town, where they discover she is a Swedish woman who had visited the town 20 years ago. Her appearance causes some consternation among the remaining locals, who remembered her. She hasn't aged a bit, she looks like she did 20 years ago. Someone calls Sweden and finds the same woman who had visited the area 20 years ago is living with her son. Who is this woman who appears out of nowhere? A local ambulance driver and her farmer husband, as well as her father, have also stayed behind. One day she finds a woman in a shed covered in ash and mud. It's her wilder, older sister who went missing and was presumed dead a year before, when the volcano first erupted. She can't say where she has been for a year. A geologist working at the glacier station is divorcing his wife. They lost a young son three years ago in an accident, and the rift caused by this has driven them apart. He finds his young son walking around the station one night, covered in mud and ash. Why are all these people (and others) all reappearing? They are Changelings, a copy of the other person, with all the memories the other person had. All are back for a reason, to serve a purpose. Some Changelings are evil, some aren't. Well done.