Sherlock's Challenge

You and a few friends excitedly knock on the door of 221B Baker Street in London to meet your favorite detective Sherlock, when the door creaks open! Tentatively you step inside and start up the stairs. As you enter the study Mrs. Hudson breathlessly appears behind you and exclaims, “We’ve been expecting you! Sherlock and Watson have left you with a challenge! If you accept you will have the opportunity to meet them both in person. All the clues you need are located in the study." She concludes with, "Will you accept the challenge?" You begin to explore the study and then slowly respond to Mrs. Hudson, “Yes, we believe we will…this is a most unusual challenge, a most unusual challenge indeed.”