Sherlock Holmes and Dr Watson sit at their breakfast table discussing a heavy walking stick left behind by an unknown visitor the previous night. Holmes invites Dr Watson to examine the cane and deduce the character and habits of its owner. Dr Watson suggests that the visitor is a successful, elderly country practitioner who does much walking and received the stick as a presentation from a local hunt. Holmes praises Dr Watson for stimulating his own thoughts, but proceeds to correct several of his conclusions through closer observation.
Holmes deduces that the inscription refers to Charing Cross Hospital rather than a hunt, and that the presentation marked the owner's departure from the hospital staff to start a private practice. By analyzing the wear on the stick and the date of eighteen eighty four, Holmes concludes that the owner is a young man under thirty, amiable, unambitious, absent-minded, and the owner of a medium-sized dog. Dr Watson checks the Medical Directory and confirms that the visitor is Dr James Mortimer, a medical officer and former house-surgeon from Dartmoor.
Dr Mortimer arrives unexpectedly at their door, eager to retrieve his lost stick and expressing immense professional admiration for Sherlock Holmes. He corrects minor details regarding his presentation, explaining that he received the stick from hospital friends upon his marriage, which forced him to abandon consulting work in town for a country practice. Dr Mortimer is revealed to be a tall, thin man with a beak-like nose and an enthusiastic interest in anthropology and phrenology. After marveling at the shape of Holmes's skull, Dr Mortimer explains that he has sought out the famous detective to consult him on a serious and extraordinary problem.