These sources are excerpts from the book, "A Duty to the Dead" by Charles Todd, which is a historical mystery novel. The text includes the dedication, a table of contents showing twenty-one chapters, and the beginning chapters that establish the narrative's time period—World War I, starting in November 1916. The story follows a nurse, Bess Crawford, who survived the sinking of the Britannic and is attempting to fulfill a promise to a dying patient, Arthur Graham, which leads her to his family in Kent and the investigation of a decade-old murder involving Arthur's brother, Peregrine. The excerpts focus heavily on mystery and intrigue, as Bess discovers a family conspiracy surrounding Peregrine’s commitment to an asylum and the true killer of a housemaid named Lily Mercer. The text concludes with a revelation that the true killer is likely Arthur's half-brother, Timothy, and Diana's postcard suggesting a future meeting with an officer recovering at Dover Castle.