In general, it was an ordinary, even typical late evening in the capital of England called London. At number 221B Baker Street, Sherlock Holmes sat in the living room on his favorite armchair and looked at the flames in the fireplace, as usual thinking about a new case that the police could not solve again, while his assistant John Watson was wandering somewhere. around the city, as he went out to buy groceries.

In an instant, a bell rings and a knock on the door from below on the first floor. As usual, Mrs. Hudson went to open the door to the guest who was brought to this mysterious house. Having let the guest in, the homeowner herself went back to her room, and the guest went up the steps, right into the living room where the detective was.

When Sherlock heard the sound of the door closing, and then muffled footsteps were heard on the stairs, he instantly looked towards the door, expecting an uninvited guest at such a late hour and Sherlock was sure that it was not his best friend John. — “Interesting...” — Sherlock Holmes muttered to himself, staring at the door.