The arrival of an enigmatic stranger at a New Year's Eve gathering triggers a series of investigations that challenge the perceptions of the observant Mr. Satterthwaite. Mr. Satterthwaite, a man who prides himself on his ability to read the complexities of human behavior, finds his usual social routine disrupted by the sudden appearance of Mr. Quin. This mysterious figure acts as a catalyst, drawing Satterthwaite into various puzzles and human dramas that require a keen eye for detail. The narrative unfolds through a series of interconnected short stories, utilizing Satterthwaite as the primary lens through which the reader experiences the uncanny influence of his companion.

This collection is widely recognized as a departure from the author's more conventional detective works, leaning into the atmospheric and the slightly surreal. Readers often note the unique dynamic between the mundane Mr. Satterthwaite and the ethereal Mr. Quin, which provides a distinct flavor compared to the author's more famous sleuths. The stories are frequently praised for their clever construction and the way they reveal the hidden depths of seemingly ordinary characters. Critics often highlight the collection as a testament to the author's versatility and her ability to experiment with the boundaries of the mystery genre.