Jabez Wilson came to consult Sherlock Holmes because he had heard that the detective would sometimes help people for nothing if their cases interested him. After telling his story, Wilson says:
"I did not wish to lose such a place without a struggle, so, as I had heard that you were good enough to give advice to poor folk who were in need of it, I came right away to you.”
Wilson tells Holmes and Watson a long tale about how he came to be employed by the Red-Headed League at a salary of four pounds a week for doing the purely nominal work of copying articles out of the Encyclopedia Britannica. He enjoyed the easy work and the money for eight weeks, and then he was shocked and flabbergasted when he found a note on the office door stating that the Red-Headed League had been dissolved. He tried to trace the man who had employed him, a Mr. Duncan Ross, but found that the forwarding address the man had left was false. Wilson's main objective is trying to get his job back, because four pounds a week for working only four hours a day was a bonanza. But even if he can't get the job back because the Red-Headed League has permanently gone out of existence, he would like to find out what the hoax was all about. As he tells Holmes and Watson, who are both amused by the story:
“No, sir. But I want to find out about them, and who they are, and what their object was in playing this prank—if it was a prank—upon me. It was a pretty expensive joke for them, for it cost them two and thirty pounds.”
Apparently Wilson does not think he has much chance of getting his old job back. Even a man as dull-witted as Wilson can see that the whole thing was a hoax. The so-called Red-Headed League had been nothing but a rented office with a table, chair, and a single volume of the Encyclopedia Britannica. Wilson had even had to supply his own paper and ink. But he has a temper. He has brilliant red hair, and this feature may have been intended to suggest that he was hypersensitive. Holmes sees a lot more in Wilson's story than Wilson realized it contained. Holmes suspects that the new assistant who first called Wilson's attention for the ad for red-headed applicants to fill a vacancy in the League of Red-Headed Men is a criminal named John Clay and that Clay must have wanted to get Wilson out of the way for four or five hours a day because he was doing something illicit at Wilson's pawnshop. That is why Holmes agrees to take Wilson's case on a pro bono basis.
Holmes quickly finds out that Clay and a cohort are digging a tunnel to get into the basement strong room of a nearby bank which currently has a huge fortune of thirty-thousand pounds in French gold coins in storage. So Wilson's simple problem leads to the arrest of John Clay, "the murderer, thief, smasher, and forger," and the prevention of a major bank robbery.
The author, Sir Arthur Conan Doyle, often had Watson remind his readers that Sherlock Holmes only took cases that interested him and was not particularly concerned about money. This gave Doyle an excuse for introducing clients from all walks of life, some of whom, like Wilson, could not afford to pay the high fees a detective of Holmes' caliber would merit. As a result, the Sherlock Holmes stories cover the whole spectrum of Victorian English society and bring him in contact with all sorts of unusual characters. Jabez Wilson is a good example. Some of Holmes' clients are wealthy men, even members of the nobility. They can afford to reward Holmes handsomely for his services, and this is what makes it possible for him to enjoy a leisurely existence and only accept cases that, for one reason or another, intrigue him.