Short summary - The Adventure of the Cardboard Box
Sir Arthur Ignatius Conan Doyle
An unmarried woman receives a box with human ears in the mail. Sherlock Holmes discovers that the ears were sent by the jealous husband of this woman’s sister, cutting them off from his wife and her lover.
Miss Susan Cushing, an unmarried woman of fifty who leads a secluded lifestyle, receives a small parcel from Belfast by mail. In a box filled with coarse salt, there are two cut off human ears. Miss Cushing's suspicion falls on three medical students, whom the woman rented rooms several years ago and refused because of their indecent behavior, especially since one of the students lives in Belfast now. Inspector Leystred, who is charged with conducting this case, turns to Sherlock Holmes for help.
The great detective visits Miss Cushing and inspects the box. He notices that the box is tied with tarred twine, which is tied with a sea knot. The address is spelled out in rude masculine handwriting. Holmes also notes that the ears are not paired, one with a hole for the earring belongs to the man, and the second to the woman. The ears were cut off with a blunt instrument, while a medical student would have performed a more professional amputation. In addition, the ears of the corpses would be saturated with a special solution. This is not a joke, but a serious crime.
The great detective is talking to Miss Cushing. He learns that she has two younger sisters - Sarah and Mary. Mary married the steward Jim Browner, who sailed on the South American line, but soon transferred to a ship cruising between Liverpool and London to be closer to his wife. Jim drank heavily, quarreled with his wife's sisters, and Miss Cushing does not know what is happening to them now. Sara is also not married, but the sisters do not get along. At one time, Sarah lived with Mary, then with Susan, but recently the sisters parted.
Sherlock Holmes visits Sarah, but the woman is seriously ill and cannot accept anyone.
The great detective asks Inspector Leistred to arrest Jim Browner. Examining the box, he decided that the person who sent it was a sailor. Comparing the severed female ear with Miss Cushing's ear, Holmes concluded that the murdered woman was her relative. Browner, a sailor, an unbalanced person and a drinker who loves his wife, is quite capable of killing his wife and her lover out of jealousy.
Arrested Browner confirms Holmes' hunch. She and Mary got married, but Sarah in love with him interfered with their family life, and Mary had a man. Maddened by jealousy, Jim killed both of them, and sent a terrible package to Sarah, not knowing that she now lives at a different address. The arrested person asks not to put him alone - if he closes his eyes, he sees his victims.