The narrator recounts a lifelong betrothal to Cordélia, their youthful bond, separation, and eventual marriage, after which subtle changes in her behavior provoke anxiety. A portrait, mysterious gifts and nocturnal events lead him into investigations that uncover hidden rooms, thefts, duels, and confrontations; acquaintances and a physician figure into the unraveling. Episodes alternate domestic happiness and mounting suspicion until a climactic last visit and a terrible tale reveal motives and concealed objects, including a golden axe, resolving the mystery and exposing how appearances and secrets shaped their fate.