The novel chronicles the story of Ryuji, a sailor with vague notions of a special honor awaiting him at sea. He meets a woman called Fusako, with whom he falls deeply in love, and he ultimately decides to marry her. Fusako's 13-year-old son, Noboru, is in a band of savage boys who believe in "objectivity", rejecting the adult world as illusory, hypocritical and sentimental.
As Ryuji begins to draw close to Fusako, a woman of the shore, he is eventually torn away from the dreams he's pursued his entire life. Noboru, who shares an especially close bond with his mother through a voyeuristic ritual, hates the idea of losing his mother to a man who has let his hope and freedom die. This anger and fear of loneliness translates into terrible, savage acts performed by Noboru and the gang of which he is a part.