The only one of Sayers' twelve major crime novels not to feature Lord Peter Wimsey, her most famous detective character, written in collaboration with Robert Eustace. This is an epistolary novel, told primarily in the form of letters between some of the characters. This collection of documents — hence the novel's title — is explained as a dossier of evidence collected by the victim's son as part of his campaign to obtain justice for his father.
Dorothy L. Sayers published "The Wimsey Papers" in
The Spectator
in 1939 and 1940, purporting to be between characters from the Wimsey novels. Aside from their interest to fans of Sayers, who would like to know more about her characters and about her views on the war, they're also interesting pieces of social history — these must be one of the last few pieces of writing where the word 'propaganda' is used in a neutral meaning, for example.