Sherlock Holmes and Dr. Watson are sitting on either side of the fire in his lodgings at Baker Street discussing criminal psychology and deduction. Holmes explains to Watson, the more complicated and interesting crimes are usually the seemingly insignificant, everyday incidents that escape the public’s notice. Holmes says “The bigger the crime, the more obvious, as a rule, is the motive”. Watson, not fully convinced, listens as his friend expounds upon the importance of small, overlooked details for the key to a mystery. During their conversation, Holmes and Watson are visited by a young woman named Mary Sutherland, who is in need of help in finding a missing person. Miss Sutherland explains to Holmes that her stepfather, Mr. James Windibank, disapproves of her seeking help, but she is desperate to find Mr. Hosmer Angel. She and Angel first met a ball, then later became romantic. Miss Sutherland explains "Angel is a soft-spoken, shy gentleman. Due to his very sensitive eyes, he wears sunglasses and comes out only at night". After her stepfather left for France, Angel approached Miss Sutherland with a marriage proposal, which she accepted. However, on the day of the wedding, he disappears.