In the early spring of 1888, Dr. Watson invites Sherlock Holmes to a walk in the park. Upon their return to Baker Street, they learn from the footman boy that they were visited by a very nervous gentleman who, having waited a while for Holmes, left the house, promising to return soon. The nervous visitor forgot his smoking pipe in the living room, and Holmes, using his deductive method, makes several subsequently confirmed conclusions about the appearance and character of the guest.
The nervous visitor is Mr. Monroe, the hopshopper. He asks Holmes to help him understand the difficult family situation. Three years ago, Monroe meets a certain Effie Hebron, a twenty-five-year-old widow of a lawyer from Atlanta, USA. At one time, in Atlanta, an epidemic of yellow fever broke out, during
Six weeks before Monroe’s visit to Holmes, the following occurs: Effie asked Monroe £ 100, but refused to explain why she needed this amount. After a few more days, during the walk, Monroe sees that the uninhabited cottage next to the villa, where they live with his wife, is occupied by somebody, since near the cottage there are many knots and suitcases.
The interested Monroau walks near the cottage, hoping to see his new neighbors, but suddenly in a second-story window he sees a horrible, deadly-yellow face. Monroe decides to get acquainted with the neighbors, but the woman who opened the door, dryly and rudely cut off Monroe’s attempts to talk to her. At night, Monroe, disturbed by the vision of a terrible yellow face, sleeps very badly. And suddenly he realizes that his wife is furtively leaving the house in the middle of the night. On her return, Monroe directly asks her about it, but his wife, clumsily lies to him that she supposedly just went out to get some fresh air.
The next day, Monroe, returning after a short absence from home, sees his wife emerging from a mysterious cottage. The wife explains this by simply visiting her new neighbors, but when Monroe attempts to enter the cottage, Effy begs him not to do so. Monroe agrees, but sets a condition for the wife: never again go to visit this strange house. And when he and his wife go to their villa, Monroe turns around and sees a man with a terrible yellow face watching them through the window.
Two days later, Monroe, returning from work early, does not find his wife at home. Rightly judging that she, most likely, is in a mysterious house, Monroe breaks into the cottage, but finds no one there. But in the room where the mysterious creature with a yellow face was supposed to be, Monroe discovers a photo of his wife, made at his insistence three months ago. Returning home, Monroe gives his wife a charge of violating her promise and leaves the house. After that, Monroe goes to London, for help to Sherlock Holmes.
Extremely interested in this story, Holmes asks Monroe about her first husband, Effi. But Monroe confirms that he saw evidence of his death. Next, Holmes suggests that Monroe return home, carefully follow the strange house, but do not make more attempts to break in there. And Holmes himself promises to come tomorrow with Watson for the final resolution of this mysterious affair.
After leaving Monroe Holmes explains to Watson his vision of this puzzle. Most likely, Effie Monroe’s first husband did not die, but was either mentally ill or leprous. And, probably, someone, knowing this terrible secret, brought her first husband to England, settled him in a cottage and began blackmailing this Effi, extorting money. Such a scenario, according to Holmes’s firm conviction, is the most logical.
The next evening, Holmes and Watson come to Norbury, where they are met by Monroe. He reports that he was following a mysterious house and offers to go there immediately to find out everything. Already before the very door of the cottage, the way to them is blocked by Effie Monroe, who begs her husband not to go in. However, Monroe does not listen to her, and the three of them, together with Holmes and Watson, enter the room on the second floor, where they find a little girl standing with her back in a red dress and long white gloves. When a girl turns her face to them, it becomes clear that the “terrible yellow face” is a mask put on the child. Holmes removes the mask from the girl and it turns out that the girl is a Negress.
Entered by Effie Monroe explains everything. This is her daughter from the first marriage, which survived during the epidemic of fever and which Effy secretly brought from the US, because she was very missed by her little daughter. Effi settled her daughter along with a faithful servant next to her in the cottage. John Hebron, Effie’s first husband, was a Negro, and at that time, because of racial prejudice, marriage between people with different skin color was considered shameful, as was the presence of a “white” woman with a “black” child. But Mr. Monroe behaves extremely nobly, he takes the girl and his wife by the hand and offers to talk about everything at home. It is obvious that the shaken marriage was safely restored and a small Negro woman will find in Monroe’s face her second father.
Holmes invites Watson to quietly retire, and already after returning home asks Watson to remind him of this case, if suddenly Watson appears that Holmes either relies too much on his abilities or does not conduct a thorough investigation of any riddle. So Holmes makes it clear that even a great detective can sometimes be mistaken, and that even a great detective needs to be reminded of this occasionally.