Holmes and Watson are at 221B Baker Street when they are accosted by a man described as a “huge negro,” Steve Dixie—an aggressive member of a criminal gang, who warns Holmes not to interfere in any business in Harrow. As it turns out, Holmes has indeed been engaged on a case in this very area. Dixie is described by Watson with a casual racism common to the time, and Holmes, although under severe provocation, is uncharacteristically offensive to him. Dixie (a historical nickname for America’s southern states) calls Holmes “Masser,” a term that was often used by slaves in the US to address their masters. He informs Holmes that he has been sent by Barney Stockdale, a senior member of the Spencer John gang. But Holmes believes that the entire gang has been hired by another, more formidable person.

Holmes and Watson travel directly to visit a new client—Mrs. Mary Maberley, a widow living at The Three Gables, a house in Harrow Weald—who needs Holmes’s advice. Her son Douglas, formerly an attaché at the embassy in Rome, died recently, and she received a strange offer soon afterward. An agent, on behalf of a client, has asked to buy her house, its entire contents, and all of her personal effects. Holmes is instantly suspicious, surmising that the person must want something that is hidden inside the house.

During the interview, Holmes unmasks Mrs. Maberley’s servant, Susan, as another gang member. From this he concludes that the notorious gang is being employed to threaten the widow, and that the instigator must be someone who is familiar enough with the London underworld to employ Spencer John and his henchmen to intimidate Mrs. Maberley. After questioning Susan, Holmes suspects that the instigator may well be a wealthy woman, rather than a man. He then notices Douglas’s trunk in the hall, recently arrived from Rome, and concludes it may contain the desired items, as the intimidation began just after his death, when the trunk arrived.

Surprisingly, Holmes suggests that Mrs. Maberley search the trunk rather than investigating it himself. For safety, he recommends that she invite her lawyer, Mr. Sutro, to stay the night. But the house is burgled that evening, the thieves targeting Douglas’s trunk and stealing a manuscript. Just one page of 245 remains, and it is clearly the end of a lurid story of love and rejection; strangely, as Holmes notes, the tale shifts from the third person narrator to the first person toward its end. He is edging closer to solving the mystery, but has yet to discover who is behind it.

Holmes consults scurrilous gossip columnist Langdale Pike, who has an unrivaled knowledge of London society, for information. This leads him to the home of Isadora Klein—a beautiful, extremely wealthy South American widow and sexual adventuress. He learns that the stolen manuscript—now a charred pile of ash in her fireplace—was in fact Douglas’s account of his doomed love affair with her. He had become “intolerable” when Isadora declined to marry him, and in a heartbroken rage he had decided to write and publish his manuscript in order to ruin her. She is now due to marry a young English lord and knows that the story would jeopardize her reputation and her quest for a British title. And so she enlisted the help of the Spencer John gang to obtain the compromising manuscript for herself.

Isadora Klein, played here by Claudine Auger in the Granada TV series, is an exotic and uninhibited femme fatale, yet one whose wiles are wasted on Holmes.

Unlike so many of the women Holmes encounters, Isadora is neither vulnerable, in thrall to a man, nor in any way dependent. In their final showdown, finding him “immune” to her seductive skills, she is honest about her reasons for soliciting the manuscript, claiming she had resorted to theft only when “everything else had failed.” And while Holmes remains steadfastly disapproving, he clearly feels some sympathy for her predicament—perhaps Douglas’s vengeful plan seemed too harsh a punishment for ending their love affair. Holmes extracts a promise from her to pay for Mrs. Maberley to travel around the world (a lifelong dream), warning Isadora of the dangers of her behavior: “You can’t play with edged tools forever without cutting those dainty hands.”