I’m not going to give away any major spoilers, but if you don’t really know anything about this film going into it, I’d advise you don’t read this review until after you’ve watched it, because just describing the set-up gives a bit away.
An entomologist is out in extremely rural dune country, searching for sand bugs. He comes across some dune people (I came to think of them sort of like a “hill people” stereotype if it were an American…