"The Red-Headed League" is a short story by Sir Arthur Conan Doyle in which Sherlock Holmes takes the case of a businessman who feels that he's been duped.
A small business owner named Wilson tells Sherlock Holmes how a man named Spaulding convinced him to take a job with The Red-Headed League.
The League pays Wilson to copy out the Encyclopedia Britannica in longhand. Wilson does this for seven weeks, up until the League is disbanded.
Sherlock realizes that Spaulding just wanted Wilson out of the shop so that he could dig a tunnel into the nearby bank. Sherlock apprehends Spaulding.
