: A doctor rents an apartment with a private investigator. Investigating a crime with him, the doctor keeps a diary from which the public learns about detective Sherlock Holmes.
After receiving a medical degree, Dr. Watson leaves to fight in Afghanistan. After being wounded, he returns to London. Constrained in funds, Watson is looking for an inexpensive apartment. A familiar medical assistant introduces him to the employee of the chemical laboratory at the hospital Sherlock Holmes, who rented an inexpensive apartment and is looking for a companion, since he can’t afford to pay one. Holmes is characterized as a decent man, but somewhat eccentric. He is a first-class chemist, but enthusiastically studies other sciences.
The doctor catches Sherlock Holmes studying blood stains. Thanks to its discovery, the type of spot can be determined, and this is important for forensic medicine.
For several weeks, Holmes leads a measured lifestyle. He spends whole days in the hospital, and then walks. His personality arouses interest in Dr. Watson. A wide variety of people come to Holmes, including the Scotland Yard Inspector Lestrade.
Once at breakfast, Watson reads an article that says that you can determine the profession of a person and his character by clothes and hands. He tells Holmes that this is nonsense, to which he replies that he wrote the article, and,Being a one-of-a-kind detective consultant, he applies this method in practice. He applies his theory to Dr. Watson, saying that he served in Afghanistan. According to the bearing, Holmes determines that Watson is a military doctor, and from his swarthy face and white wrists that he went to the tropics. Watson is unhealthy and injured, therefore, he was in the war that is now going on in Afghanistan.
Holmes receives a letter from Gregson Police Inspector in the mail. A corpse of a man was found in an abandoned house. He had a business card with the inscription: "Enoch Drebber, Cleveland, USA." There is no sign of robbery or violence, although there are bloodstains on the floor. Taking Watson, Holmes arrives at the crime scene.
First, the detective examines the sidewalk, the neighboring house and the soil. Then he enters the house and examines the corpse, whose face is disfigured with a grimace of horror and hatred. Near the corpse, Holmes finds a female engagement ring, and in his pockets a book with an inscription from Joseph Stangerson and a letter: one to Drebber, the other to Stangerson. Arriving inspector Lestrade discovers on the wall the inscription "RACHE", made in blood. The police conclude that this is the unfinished name of Rachel, but Holmes examines the inscription, the dust on the floor and smiles mysteriously. He says the killer is a tall man with small legs. The detective also reports which shoes he wears, which cigars he smokes, and adds that the killer has a red face and long nails. He arrived in a cab with a horse with three old horseshoes and one new one. The killer used poison, and "RACHE" in German means revenge.
On the way home, Holmes explains to Watson that he knew about the cab and the horse in the footsteps on the sidewalk. Since usually a person writes at the level of his eyes, then the inscription can determine growth. Seeing that the plaster near the inscription was scratched, Holmes realized that the killer had long nails. And finding ashes on the floor, he determined the sort of cigars, as he was engaged in the study of ashes.
The constable, who was on duty that night, says that when he saw the light in an empty house, he went into it, found a corpse and left. At this time, a red-headed drunkard was hanging out on the street near the gate. Holmes realizes that it was a killer who decided to return to the house for the ring. He advertises to the newspaper about finding a ring. An old old woman comes to Baker Street and declares in a rude manly voice that this is her daughter's ring. Holmes gives her the ring and sets off, but loses sight of her. He tells Watson that this is not an old woman, but a disguised young actor.
Police put a note in the newspaper that Enoch Drebber arrived in England with his secretary Joseph Stangerson, and the murder was politically motivated. Competing with Lestrade, Gregson tells Holmes that he arrested a certain Arthur Charpentier for the murder. Finding a cylinder near the corpse, he went to the shop where the hat was purchased and found out the address of the buyer. Drebber rented an apartment with his mother Arthur Charpentier, behaved incorrectly in relation to his sister, and Arthur drove him out. Inspector Gregson met with Arthur and did not have time to ask anything, as he asked if the police suspected him of the murder of Drebber.Gregson suggests that Arthur hit Drebber with a stick in the stomach, leaving no trace on the body. Drebber died immediately, and Arthur dragged him into the house, leaving an inscription and a ring to confuse the tracks. Meanwhile, Lestrade appears with the news of the Stangerson murder in a hotel.
Arriving at the crime scene, Holmes and Watson see that death came from a stab in the side, and the same bloody inscription was on the wall. Lestrade reports that the killer was seen, his appearance coincides with the description of Holmes. A telegram from America with the text “J. H. in Europe ”, but without a signature, and on the table is a box with two pills, upon seeing which Holmes comes to life. He is trying pills on a terminally ill dog. One of them is harmless, the second is poisonous. Holmes says he knows who the killer is. A gang of street boys finds a cab for him, and Holmes handcuffs the cabman, introducing him as a killer.
Aortic aneurysm Jefferson Hope tells his story. He loved a girl who lived among the Mormons, although neither she nor her father respected their religion. Hope wanted to marry her, but the Mormons Drebber and Stangerson wanted her to marry their sons. They killed her father, and the girl was forced to marry. The unfortunate died of grief a month later, and Hope vowed revenge. For many years he hunted them down and finally found them in London. Arranged to work as a cabman, he lured the drunk Drebber into an empty house and offered a choice of two pills. One was harmless, the second was poison. Frightened, Drebber grabbed a poison pill and died.Hope left the house, but forgot the ring there. When he hunted down Stangerson, he refused to take the pills, and Hope killed him with a knife.
Did not live up to the trial, Hope dies in a prison cell. A note appears in the newspapers that police inspectors Gregson and Lestrade deftly caught the killer. But Dr. Watson keeps a diary in which he writes down all the facts, and the public finds out who actually caught the criminal.
