: A person funding the research of a young doctor is found hanged. Sherlock Holmes discovers that the benefactor once robbed a bank and betrayed his accomplices, who avenged him.

Sherlock Holmes seeks help from Dr. Percy Trevelyan. After graduating with honors from the university, the young doctor wanted to devote himself to the study of nervous diseases, even wrote a monogram, but he did not have the means to carry out his plan. Suddenly, a certain Mr. Blessington came to him, suffering from a heart disease and in need of constant medical supervision. Blessington offered Percy to fund his practice, on the condition that Percy would give him three-quarters of his earnings.

Two years have passed. The case turned out to be profitable. Percy enriched Blessington and advanced himself. Having settled in the same house with the doctor, Blessington led a secluded lifestyle, did not communicate with anyone and rarely went out. Without punctuality, he still checked the patient book every evening and took three-quarters of his earnings, hiding the money in a chest in his room.

A few weeks ago, Blessington found out about some kind of robbery and came home very excited. He immediately put additional bolts on the windows and doors.Percy decided that he was afraid of someone, but Blessington was just starting to swear at all questions.

Two days ago, a Russian nobleman suffering from catalepsy turned to Percy for help. The patient was brought by a son who remained in the corridor while his father was examined by a doctor. During the examination, the patient began an attack. Percy went out for a few minutes to get the medicine, and when he returned, there were no more visitors.

Today, a Russian nobleman and son again came and apologized for the sudden departure. Having regained consciousness, the father did not remember what was happening to him, and hastened to leave the unfamiliar room on the street, and the son decided that the reception was finished, and left behind his father. Blessington was not at home during these visits. Arriving home, he went into his room, and then burst into Percy’s office in panic. Someone was in his room: there were traces on the carpet. Percy realized that while his father was in his office, his son went into Blessington's room. Having calmed down with difficulty, Blessington asked Percy to tell Sherlock Holmes what had happened.

The great detective and Dr. Watson visit Blessington. A regular patient begs to protect him from robbers, but Holmes advises telling the whole truth, only then he can help.

The case interests Holmes. He suggests that visitors decided to get to Blessington, which is panicky afraid of them. By pure chance, during their visits, he was not at home. One feigned catalepsy, and the second entered the master’s bedroom.

In the morning it becomes known that Blessington hanged himself at night.After examining the room, the great detective concludes that there was a murder. There were three criminals, two of them, most likely, were those who pretended to be Russian nobles. Let in their servant boy, who disappeared.

By evening, the police find a servant, and Holmes identifies the perpetrators. A few years ago, a gang of five robbed a bank. One of the gang members, Blessington, became a scammer, one was hanged, and three were released ahead of schedule. Now they hunted down Blessington and took revenge on him.

The police do not find killers. Scotland Yard decides that they sailed from England on a boat that disappeared off the coast of Portugal.