In 2008, the murder of Canadian model Diana O'Brien in her Shanghai stairwell rocked the city's Chinese and expat communities. Years later, author Mara Hvistendahl revisited the story, interviewing the family of the victim and accused killer, police investigators and other models working in China.

Her new book, "And The City Swallowed Them," looks at the world that brought two different kinds of newcomers together—foreigners, including young models fighting for emerging opportunities in high fashion, and China's...