Closed circle of suspects


The closed circle of suspects is a common element of detective fiction, and the subgenre that employs it can be referred to as the closed circle mystery. Less precisely, this subgenre – works with the closed circle literary device – is simply known as the "classic", "traditional" or "cozy" detective fiction.
It refers to a situation in which for a given crime, there is a quickly established, limited number of suspects, each with credible means, motive, and opportunity. In other words, it is known that the criminal is one of the people present at or nearby the scene, and the crime could not have been committed by some outsider. The detective has to solve the crime, figuring out the criminal from this pool of suspects, rather than searching for an entirely unknown perpetrator.

History

This type of narrative originated in British detective fiction. Agatha Christie's The Mysterious Affair at Styles has been credited as a work that started this trend. Other writers of that period, dating to the first half of the 20th century, a time known as the Golden Age of Detective Fiction, reliant on the closed circle and related literary devices include Agatha Christie, Dorothy L. Sayers, Margery Allingham and Ngaio Marsh, G. K. Chesterton and Americans S. S. Van Dine and Ellery Queen.
Those early closed circle mysteries preferred a common setting: a British country house. The country house was a common enough element that closed circle mysteries set in such a location are sometimes known as "country house mysteries". The persons involved were also commonly part of the upper class, generally the landed gentry. Other settings than the country house are possible, such as ships, trains, islands, and so on. The requirements for the setup of the mystery enforce certain limitations on the genre. Certain settings are frequently represented in the genre, typically involving upper-class characters to whose properties outsiders have limited access. The numbers of suspects vary, from a group as small as four or five, to all the passengers of a train, coach or wagon. The location may be temporarily isolated by a snowstorm or similar, and may or may not have a working telephone, but generally has a working power supply as well as servants to cook and clean
After the Second World War, the closed circle mystery became less common as other types of crime novels rose to prominence; nonetheless, writers such as Rex Stout, Lucille Kallen, Cyril Hare, Jonathan Gash, and Simon Brett have employed the device in their fiction.
While the closed circle is a common device in literary fiction, it is a much less common occurrence in actual criminal investigations.

Country house mystery

Examples of the "Country house mystery" from the Golden Age of Detective Fiction are:
More recent examples include: