[Sounds of civilization off screen]
A school teacher and amateur entomologist is looking for insects in the sand dunes, in Japan. Missing the last bus to return to civilization, a men finds him a place to stay for the night - The house of a young woman that lives in a pit in the sand, reacheable only through a whole. On the next day, he tries to return, only to find that he was trapped there.
Now he is in a trap himself...
This movie is based on a book with the same name, written by Kobo Abe. The spcreenplay was also authored by Abe.