I think that it operates for 'one of those' outfits that do daring deeds in dangerous places and it has been anonymised for hiding in plain sight.
The only DHC-7 that comes to mind was Brymon operating into LCY years ago, but I also remember them with Tyrolean (?) in the past. Oh and Widerōe in the very north of Norway going to Svalbard. No others come up. Anyone ? Perhaps some feeder airlines in the USA ?
Just remembered! Hawaiian Airlines, but that was 35 years ago.