MacDuff was a retired college professor who dabbled in solving real-life murders, often as a volunteer consultant to local police. Armstrong’s children loved this book because three of the child characters were loosely modeled on them. They often challenged friends to read the book and decide which character was each of them. It wasn’t hard. The plot was around a divorcee with six children where suddenly a friend dropped dead from poison. The children were all suspects at one time or another.
They also loved this story because the location was basically their house in New Rochelle, NY.
Armstrong surely loved writing this story because of these factors, but the real intention was to continue the series where each succeeding book would feature one of the six kids. However, due to less than robust sales, her agent advised switching to the suspense genre, and, starting with The Unsuspected (see post of December 5, 2021), the advice turned out to be excellent as that story launched her career.