Dead Voices

Dead Voices by Katherine Arden

The protagonist's father gets to bring people up to a new ski resort for a pre-opening. There is a bad snow storm, so they are the only ones to make it out there. The next day a "journalist" appears - though he is a ghost hunter. The place is haunted. Looking in mirrors can cause people to end up in the netherworld. They think they are stuck there. In the end, they find having something both in and out of the netherworld can free them. A fire helps get them out. Story is well written, but not up my tree.