This 1934 novel was recently reissued in the American Mystery Classics series. It was originally published in England, even though King was an American. This is its first full American edition.
King was a psychologist. He wrote four Obelist detective stories. "Obelist" is a word he invented that, depending on when he was quoted, meant either "of little or no worth" or "one who views with suspicion". Each story features Michael Lord of the NYC police and a variety of psychologist representing different schools of psychology.
This has a great mystery story premise. Transcontinental Railroad is introducing a new luxury cross country train. The inaugural trip from New York to San Francisco is a special celebrity/VIP crowd.
One of the special features is a swimming pool in a railroad car. A wealthy industrialist passenger, Sabot Hodges, is found dead in the pool early on the first morning of the trip. Lord needs to determine if it was an accident, a suicide or a murder.
Each of the four specialists, a Freudian, an integrative, a Hormic and a Gestalt psychologist, come up with a theory of what happened, consistent with their school of psychology. A second shooting happens on the train and the mystery grows. This is a well-constructed fair-play mystery. One of the features is a "Clue Finder" at the end of the book which gives page and line references for each of the important clues. King also gives us several diagrams of the train and a map.
King adds in chunks of psychology, as each practitioner describes their approach. He footnotes the leading articles and books on each school of thought and provides a bibliography. We get, for example, eight pages explaining "integrative psychology".
This book is written in the shadow of the depression. There are discussions about the economy. There is ten pages on a popular economic theory called "social credit", with references to the important writing and a section on "Technocratic Economics".
Overall, this is an excellent and clever mystery with a certain amount of preaching and lecturing sprinkled in. I enjoyed it.