The story takes place on Hajima, a tiny island in Nagasaki Prefecture that once served as the base for an undersea coal mine, until those operations closed in 1974. While the island is now deserted, this tale spans a half-year period from spring to autumn of 1959, when the mine was in full swing and the island’s resident population reached a record high of 5,100. Given Hajima’s scant size at .063 square kilometers (15.5 acres), its population density in the novel’s timeframe is greater than that of Tokyo. Even today the island is known by its “battleship island” nickname Gunkanjima, because of the many tall concrete buildings that make its landmass resemble a warship.
The action begins in April, when Aramaki, 24, a cop who started his career straight out of high school, arrives to take up his new post as the junior officer in the two-man police force on Hajima. The mine on the island is operated by Mitsubishi Mining Co., whose operations run around the clock in three eight-hour shifts. The local population is divided roughly into three distinct tiers or classes: MMC management, the company’s in-house miners, and subcontracted laborers. Each group lives in separate areas, with clear distinctions in socio-economic status, and they coexist in a somewhat precarious equilibrium. The company maintains tight control over the island, with an eye to preventing labor troubles. Criminal behavior is also deterred by the fact that there is no place to run or hide; only a single ferry connects the island with the mainland. And yet the unimaginable happens.
Soon after Aramaki arrives, on the night of a full moon, a teenaged girl named Keiko, the daughter of a miner named Heizō and his wife Masue, first goes missing and then is discovered drowned. There is talk that Masue has been working as a prostitute. Masue hangs herself, and Heizō leaves the island. Since it is unclear whether Keiko died by accident, suicide, or foul play, Aramaki begins an investigation. Although an examination of the body fails to confirm assault or rape, a nurse notes that a portion of the girl’s hair has been cut off. Aramaki soon learns that a similar incident occurred eight years before, also on the night of a full moon, when the 13-year-old daughter of an MMC office worker went missing, then was found drowned; in that case, not only was a portion of the girl’s hair cut off but she turned out to be pregnant. As he continues his investigations, Aramaki learns that a miner named Hasegawa was previously a police detective in Tokyo, and that he had been investigating a series of five similar murders when he was forced to resign from the force due to injury. All five of the murders took place on the night of a full moon, and the young female victims had all had portions of their hair cut off. Convinced that the murders are linked, Aramaki focuses his suspicions on island residents who moved there from the nation’s capital at least eight years before. In August, another girl goes missing on the night of a fireworks display, but is ultimately found before she comes to harm.
The following month, as a typhoon rages over the island, Aramaki pursues his suspect, only to have him get away. The perpetrator turns out to be the owner of a restaurant on the island?a man who had in fact been very kind to Aramaki.
The story begins with a crime that ought not be possible on such an isolated island, and the investigation that follows is complicated by the closed, insular relationships among island residents. One suspect after another emerges from the hidden past as each new fact comes to light. Readers will delight in the author’s consummate skill at playing out and sustaining the elements of suspense.