Kerewin lives in a tower overlooking the sea on the coast of the
South Island. She is isolated from her family and interacts little with the local community, but is able to live independently after winning a lottery and investing well. On a stormy afternoon, a young child, Simon, appears at the tower. He is mute and communicates with Kerewin through hand signals and notes. He is picked up the next morning by a family friend; later that evening Simon's foster father, Joe, visits Kerewin to thank her for looking after Simon. After a freak storm years earlier, Simon was found washed up on the beach with very few clues as to his identity. Despite Simon's mysterious background, Joe and his wife Hana took the boy in. Later, Joe's infant son and Hana both died, forcing Joe to bring the troubled and troublesome Simon up on his own. Kerewin finds herself developing a tentative relationship with the boy and his father. Gradually it becomes clear that Simon is a deeply traumatised child, whose strange behaviours Joe is unable to cope with. Kerewin discovers that, in spite of the real familial love between them, Joe is physically abusing Simon. Horrified, she initially says nothing to Joe, but suggests they travel to her family's
bach (holiday home) by the beach for a break. Early on in their stay she confronts Joe and asks him to go easier on Simon. Joe and Kerewin argue, and after Simon spits at Joe, she intervenes to stop Joe from beating him, using her
aikido skills. Following the incident, Joe promises not to beat Simon without her permission. They spend the rest of their time at the beach fishing, talking and drinking. After returning home from the holiday, Simon sees the aftermath of a violent death and seeks Kerewin out for support, but she is angry with him for stealing one of her prized possessions. Simon reacts by punching her; she instinctively hits him in the chest and in response he kicks in the side of her guitar, a gift from her estranged mother. Kerewin tells him to get out. Simon goes to the town and breaks a series of shop windows, and when he is returned home by the police Joe calls Kerewin, who gives Joe permission to beat the child (but tells him not to "overdo it"). Joe beats Simon severely, believing he has driven Kerewin away. Simon, who has concealed a shard of glass from a shop window, stabs his father. Both are hospitalised, with Simon falling into a coma. Joe is released quickly but sent to prison for three months for child abuse, and in the meantime Kerewin leaves town and demolishes her tower. Simon eventually recovers, albeit with some loss of hearing and brain damage, and is sent to live in foster care against his wishes. He is unhappy and continually runs away, trying to get back to Joe and Kerewin. After Joe's release from prison, he travels aimlessly. He jumps off a cliff and nearly kills himself, but is rescued by a dying
kaumātua (respected elder) who says he has been waiting for Joe. He asks Joe to take over guardianship of a sacred
waka (canoe), containing the spirit of a god, which Joe accepts. In the meantime, Kerewin becomes seriously ill with stomach pains. Although she visits a doctor who says he is concerned it may be stomach cancer, she refuses to allow him to investigate further and insists he write her a prescription for sleeping pills. After several weeks in a mountain cabin, on the point of death, she is visited by a spirit of some kind and cured. Kerewin returns to her community and takes custody of Simon. Joe also returns, bringing with him the sacred spirit. Without Kerewin's knowledge or permission, he contacts Kerewin's family, resulting in a joyous reconciliation. The final scene of the novel depicts the reunion of Kerewin, Simon and Joe, celebrating with family and friends back at the beach where Kerewin has rebuilt the old
marae (communal meeting house) and rebuilt her home, not as a tower but in the shape of a shell with many spirals. ==Themes and characters==