Sherlock Holmes was together with Watson sitting in the livingroom and they were discussing about the walking stick, which Dr. Mortimer forgot. They were tried to find out, trough the initials, more about the life of Dr. Mortimer. On the walking stick was a print of a set of teeth of a dog. Holmes knew which art of dog it was, because he saw the dog with Dr. Mortimer at the door. Holmes and Watson were discussing with Mortimer about his life.