A detective is hired after a wealthy household reports the disappearance of the wife's costly diamonds; he canvasses the house, questions family members and servants, and follows leads including contemporaneous arrests for similar second-story break-ins. The narrative unfolds as a methodical investigation emphasizing close observation, logical deduction, and domestic detail, exposing social tensions and hidden motives within the household. The plot proceeds through careful clue-gathering and analysis to reveal how the theft occurred and who is responsible.