Watson walks into Holmes's breakfast-room, where Sherlock Holmes is having breakfast. Watson examines a walking stick which a visitor, James Mortimer, had left behind the night before, after finding nobody there to receive him. Mortimer's name is engraved into the stick.
Though his back is turned to Watson, Holmes sees his friend through the reflection in his coffee-pot. He surprises Watson by addressing him, and then asks him to deduce the character of James Mortimer from his stick.
Based on the stick, Watson believes that Dr. Mortimer is an elderly, well-respected doctor who lives in the country. He further deduces that Mortimer has received this stick as a gift from a hunting club.
Holmes initially compliments Watson's detective skills, but then clarifies that he is only complimenting the way that Watson has stimulated his own thought process. Holmes examines the stick himself, and concludes that Mortimer received the stick as a gift from a hospital, rather than from a hunting club. He deduces that Mortimer was a student at this hospital, not a physician, and that he must therefore be young, not old. Further, he believes that Mortimer has withdrawn from a town hospital to begin his own practice in the country. He adds that Mortimer must be absent-minded, amiable, unambitious and a dog owner.
Astonished, Watson looks in his Medical Dictionary for public information about Mortimer. The book confirms that Mortimer is a young man who studied as Charing Cross Hospital. Holmes begins to explain how he deduced that Mortimer owned a dog, but sees a dog from his window and realizes that Dr. Mortimer has now returned to pay them a visit.
Dr. Mortimer enters, and Watson describes him as a tall, thin man with bad posture, and dressed in a messy manner. Relieved that he left the stick there and did not lose it, Dr. Mortimer reveals that he received it not on the occasion of leaving Charing Cross, but for his wedding.
First, Dr. Mortimer notes that he had heard of Holmes through his reputation for solving difficult problems. Strangely, Dr. Mortimer then compliments the shape of Holmes's skull, and tells him that it would be an "ornament to any anthropological museum" (143). He explains that he studies skull shapes.
Holmes asks why Dr. Mortimer has called on him, and Mortimer tells him that he has a most serious and extraordinary problem.