Sent in by a reader:

One time Sherlock Holmes was investigating a jewel thief. He already knew who the thief was, and just needed to find it. Fearing that he had been recognized by someone during his investigation, he sent Watson to go to the warehouse where the jewels were. When Watson go there, however, he saw an empty chest. Inside was half of an American dollar (the pyramid half was missing) with the arrows crossed out. Who got there before Watson?