The Red-headed League

Jabez Wilson, a London pawnbroker, comes to consult Sherlock Holmes and Doctor Watson. While studying his client, both Holmes and Watson notice his red hair, which has a distinct flame-like hue. Wilson tells them that some weeks before, his young assistant, Vincent Spaulding, urged him to respond to a newspaper want-ad offering work to only red-headed male applicants.

The next morning, Wilson had waited in a long line of fellow red-headed men, was interviewed and was the only applicant hired, because none of the other applicants qualified; their red hair was either too dark or too bright, and did not match Wilson's unique flame color...