Requiem for a Wren — Nevil Shute

Alan Duncan returns to Australia after the war and several years of study in England. But his homecoming is marred by the mysterious suicide of his parents' quiet and reliable parlour-maid. A search through her belongings in search of clues leads to heartbreaking revelations about the woman's identity, the death of Alan's brother Bill, and, above all, the disappearance of his brother's fiancée.