Through the crowds that were constantly increasing in size the four lads threaded their ways, two on one side of the street, and two on the other. Ahead of them was the mysterious man. He seemed to have no idea that he was being followed, and appeared only to be looking at the sights. At times the boys found difficulty in keeping within the proper distance of him, and once Ned and Frank lost him, but they soon picked him up again, and kept on. He wore a light-colored cap, which made him conspicuous in the press of people.