Schoolteacher and amateur
entomologist Niki Junpei leaves Tokyo for a rural coastal village to collect
tiger beetles and other insects. He is self-absorbed, dissatisfied with his life in Tokyo, and rude to his hosts. After a long day of searching, Junpei misses the last bus ride back to the city. The locals invite him to spend the night at their village. Junpei agrees and is guided down a rope ladder to a hut at the bottom of a sand dune, which resembles a large pit. Due to the steep slopes of the dune, the ladder appears to be the only way in or out. Junpei learns that his host, a young woman, lost her husband and daughter in a sandstorm a year ago and now lives alone; their bodies are said to be buried under the sand somewhere near the hut. The widow explains that the sand is constantly falling on the house, and without shoveling it out every day, she will be buried. After dinner, the widow goes outside to shovel the sand into buckets, which the villagers reel in from the top of the dune. Junpei offers to help, but she refuses, telling him that he is a guest and there is no need for him to help on the first day. A passer-by ominously refers to Junpei as the widow's "helper". The next morning, Junpei gets ready to leave but finds that the rope ladder has been pulled up. He tries and fails to climb up the dune. He realises that the villagers trapped him in the pit so that he can live with the widow and help her dig sand, which the village sells to a cement company on the black market. The widow is as much a slave of the villagers as Junpei is. The villagers control both of them by limiting their access to water and provisions. The widow has long resigned herself to her fate, and entreats Junpei to help her shovel the sand. Although Junpei points out that the sand is poor quality and will make defective cement, she crassly explains that it is not her problem. With the sand piling up in and around the house, Junpei finally agrees to help the widow dig; however, he continues plotting his escape. Although the widow has trapped Junpei, she also grows emotionally attached to him. The two become lovers. Junpei uses an improvised grappling hook to haul himself out of the pit. However, the villagers chase him into
quicksand, which forces him to ask his captors for help. The villagers free him and return him to the widow. Like the widow, Junpei eventually resigns himself to his situation. Frustrated with the monotony of the pit, he asks his captors to see the nearby sea every day. The villagers agree on the condition that he has sex with the widow while they watch. Junpei agrees, but the widow refuses, calling him a pervert. Junpei tries to force himself on the widow anyway, but she fends him off while the villagers watch. Through his persistent efforts to trap a crow as a messenger, Junpei discovers a way to draw water from the damp sand at night by
capillary action. His efforts to perfect the technique help him settle into an easy routine. When an
ectopic pregnancy threatens to kill the widow, the villagers take her to a doctor. They leave the rope ladder hanging, and Junpei climbs out. After going to see the nearby sea, he chooses to go back in the pit, telling himself that he can still escape later. He muses that he would like to show someone his method of water production, and the villagers would be the best audience. The film's final shot is of a police report stating that Junpei has been missing for seven years. ==Cast==