Japan's renowned woodblock prints—the ones said to have inspired Western Impressionists such as Claude Monet—are known as ukiyo-e, literally "pictures of the floating world." Ukiyo-e originated in the 17th century in Edo, the ancient name of Tokyo. They depict the most colorful aspects of the city's pleasure quarters—fierce-looking Kabuki actors and half-dressed courtesans, serene teahouses and crowded brothels.

Today the floating world goes by another name—mizu shobai, or the "water trade"—but the gist is the same. Mizu shobai encompasses the panoply of geisha houses, hostess bars, dance clubs, strip joints, no-pants coffee shops and massage parlors that characterize the night life of the Japanese capital. It's a "beautiful and suggestive term," writes Richard Lloyd Parry in "People Who Eat Darkness." Does it refer "to the drinking, which was an essential part of the nighttime experience"? Or to "the evanescence of its pleasures, flowing past like a stream"? "People Who Eat Darkness" is Mr. Lloyd Parry's riveting true-crime tale of a young, naïve and tragically unlucky Englishwoman named Lucie Blackman who lived, and died, in this modern-day floating world.

Lucie was tall, blond and beautiful. In 2000, at the age of 21, she quit her job at British Airways in London and decamped to Tokyo with her best friend, Louise. She was seeking adventure and, in these days of the mighty yen, easy money with which to pay off her debts back home. The girls got off-the-books jobs as hostesses at the Casablanca bar in Roppongi, the bright-light district that serves as the pulsating hub of the mizu shobai.

One afternoon Lucie went out on a date with an unnamed Casablanca customer and vanished. Six months later her remains were found in a shallow seaside grave. She had been drugged and apparently raped before her death. Her body had been sawed into 10 pieces. The man who was ultimately convicted of the abduction, drugging, attempted rape and dismemberment of Lucie—though not, inexplicably, of causing her death—was also convicted of eight rapes and the earlier murder of an Australian bar hostess. In the words of one of the appeals-court judges: "To violate the dignity of so many victims, using drugs, in order to satisfy his lust, is unprecedented and extremely evil."

Lucie's younger sister, Sophie, would later say that the only difference between Lucie's hostessing job and her former work as a BA flight attendant was the altitude. Mr. Lloyd Parry offers a more realistic view. The hostess bars that employ Western women in Tokyo occupy a "middle zone" in the water trade, he observes. It's the zone "in which talking and watching are the principal attractions, rather than touching." But not always. Once a foreign woman entered the mizu shobai, she "was subject to pressures and temptations that shadowed her life in Japan, whether she was aware of them or not."

People Who Eat Darkness

By Richard Lloyd Parry
(Farrar, Straus & Giroux, 452 pages, $16)

"People Who Eat Darkness" is a factual account, but it is as compelling as any thriller. The narrative gallops along, with dramatic twists, turns and half-resolutions. Joji Obara, Lucie's abductor and apparent murderer, is every bit as brilliant and terrifying as the fictional Hannibal Lecter. Obara's personal logbook of his sexual adventures, kept from 1970 to 1995, records 209 encounters. It described how he lured Japanese and foreign women to one of his homes, drugged them and then had sex with them. The phrase he favored to describe his exploits—which he insisted were consensual—was "conquest play."

Mr. Lloyd Parry, a veteran British journalist and Asia hand, spent 10 years following the hunt for Lucie's killer and Obara's trial. His reporting took him into many dark corners of the water trade, from the sleazy establishments that exploit young women from Southeast Asia to S&M clubs, "a world of manacles and excretion." It also took him into the maze of Japan's legal system, which he describes as woefully inadequate to handle such a case. Obara's trial and appeal took eight years, ending in 2008.

Tokyo is probably the world's safest city, thanks to the law-abiding Japanese people, the well-ordered nature of Japanese society, and the abundance and diligence of the local police, who are a highly visible presence. In dealing with an out-of-the-ordinary crime such as Lucie's murder, however, the police proved to be out of their depth. They were, in Mr. Lloyd Parry's words, "lamentably ill-equipped—sclerotic, unimaginative, prejudiced, and procedure-bound, a liability to a modern nation."

Mr. Lloyd Parry credits the efforts of Lucie's father, Tim Blackman, with keeping the investigation from stalling. After Lucie vanished, Mr. Blackman spent months in Tokyo pressing the police to follow up leads they had ignored and conducting a one-man media campaign to draw attention to Lucie's disappearance. His blunt, forceful presence at the many press conferences he held did not comport with conventional Japanese or British notions of how bereaved parents should behave.

The author's discussion of the effects of Lucie's murder on Tim and the rest of the Blackman family is intimate, sensitive and chilling. In the wake of the tragedy, the family unraveled. Lucie's mother, who was divorced from Tim before Lucie went to Japan, found solace in a medium who helped her "see" her daughter again. Lucie's sister attempted suicide and entered a psychiatric clinic. Her brother had a breakdown and flunked out of university. Tim eventually accepted "condolence money" from Obara in return for making a statement on Obara's behalf; he used the money to buy a yacht and spend a year sailing around the world.

Mr. Lloyd Parry asks us not to judge the Blackmans. We'd all like to think that we'd behave in an exemplary way if tested with such a tragedy, but who knows? One measure of the power of this intelligent, compassionate book is that it leaves the reader pondering that question.

Ms. Kirkpatrick, a senior fellow at the Hudson Institute and a former deputy editor of the Journal's editorial page, is the author of the forthcoming "Escape From North Korea."