Author Keigo Higashino marks 30 years since his literary debut with this, his 80th work, a scientific mystery.
A death occurs at Akakuma Hot Springs in northeastern Honshu. The deceased is a hotshot film producer, Yoshirō Mizuki, 50, on a short getaway with his wife, Chisato, 28. They were out enjoying a walk together, but she had gone back to their room to get something she had left behind; in the brief time she was gone, he succumbed to hydrogen sulfide (H2S) poisoning. A short while later, the 39-year-old struggling actor Gorō Nasuno also dies from H2S poisoning while staying at Tomate Hot Springs in the Hokuriku region, which lies along the central Sea of Japan coast. It is not unusual for H2S gas to rise through openings in the ground in the vicinity of hot springs, but in neither case did measurements taken immediately afterward show sufficient concentrations of the gas to cause poisoning.
Called in by the prefectural EPA in the case of Akakuma and by a newspaper company in the case of Tomate, environmental analyst Shūsuke Aoe examines both sites, but concludes that the deaths were freak accidents caused by the deadly gas accumulating at low spots in the terrain when the wind was calm. Police ask whether Chisato, barely more than half Mizuki’s age, might have poisoned him for his money and life-insurance payout, but Aoe dismisses the possibility: not only are there too many uncontrollable variables for the use of H2S gas as a poison in an outdoor environment, but the woman would have risked poisoning herself in the process. He finds it curious, though, that he saw the same young woman showing a photograph around and looking for a missing person at both locations he investigated.
The young woman is Madoka Uhara, 18. When Madoka was ten years old, her mother died in a tornado. Recently she has been living in a mathematical research facility, from which fellow resident and friend Kento, 20, disappeared. Evading watchful eyes, she has slipped out of the facility to try to find him. Kento is the son of film director Saisei Amakasu. When he was 12, his older sister used H2S gas to kill herself, and in the process also killed her mother and left Kento with severe brain damage that put him in a vegetative state. Madoka’s father, Zentarō Uhara, a brain surgeon, operated on Kento, resulting in a miraculous recovery?except that the boy was left with total amnesia. Rejecting any relationship to Amakasu, he had gone about building a new life for himself.
Kento’s operation involved implanting genetically engineered cancer cells along with electrodes and a special device in his brain. Besides enabling his miraculous recovery, it made him into a “Laplace’s Demon,” giving him the ability to analyze the precise state of all physical elements and predict their future course. A project was subsequently launched jointly by several different government bodies to discover exactly what happened to Kento’s brain and to see if it could be replicated. When Madoka happened to visit the research facility and met Kento, she began begging her father to perform the same operation on her: she wanted to be able to predict the kind of tornadoes that killed her mother. Overcoming his initial qualms over experimenting on his own daughter, Uhara had taken up his scalpel and succeeded in making Madoka into a “Laplace’s Witch.”
Meeting Madoka proves to be the key for Aoe to home in on the truth of what happened: were the two deaths merely freak accidents, or did somebody have a hand in bringing them about?