The novel begins with a mysterious murder in a country manor called Birlstone, where a wealthy American named John Douglas is found dead with a bullet in his head. Sherlock Holmes is brought in to help solve the case, and with the help of his trusted ally, Dr. Watson, he begins to investigate. They discover that Douglas had a secret past, having been a member of a secret society called the Eminent Order of Freemen, and as they dig deeper, they uncover a web of intrigue involving a vengeful ex-member of the Eminent Order of Freemen, a traitor within the group, and a plot to steal a fortune in gold from the local bank.