There was something towing behind the skiff by a rope. As the skiff paused, the three men pulled it into the boat. It was a large object, but the detectives could not make out at that distance what it really was. They saw the three men working over it for a while, and finally push it overboard again so the boat could tow it. When this was done the light craft was rowed down the river and the detectives lost track of it altogether. They felt rather disappointed. "What the deuce were they doing?" Harry asked. "Blessed if I could tell," replied Old King Brady, in perplexity. "Let's go back to Mason's house and wait for him to come back." Old King Brady assented. They returned to the West Thirty-sixth street residence. An hour later, as they stood on the corner, the man they suspected as Mason came along, and Old King Brady stepped in front of him. "Hold on there, my friend!" he remarked. "Let me pass!" growled the other in low, ugly tones, as he shot a savage glance at the old detective, and made an effort to go by. "Wait a moment!" persisted the officer. "I ain't got any time." "Tut-tut!" "Well, what do you want?" "I've taken a violent interest in your whiskers, sir." "Come, now, none of your guying----" "Oh, I ain't fooling. I've taken such a huge interest in your whiskers that I'd like to have a handful as a keepsake." And so saying the detective grabbed them. A slight pull dislodged them from the man's face, causing him to recoil, giving utterance to a smothered cry of alarm. Old King Brady chuckled. Holding up a false beard, he glanced at the man. "Why," exclaimed Harry, "it's Mr. Mason!" "Bless my heart, so it is," added the old detective, feigning to be very much astonished at the discovery. "How strange! Why, Mr. Mason, what in the world are you going around masquerading this way for, at such a late hour of the night?" The broker's nephew was furious over his exposure. He knew it was useless to pretend he was not the man they mentioned and he swore at them, and cried, fiercely: "That's none of your infernal business." "How angry you are. My! My! Keep cool, Mr. Mason. Wrath isn't going to mend matters for you in any way." "Get out of my path, you old meddlesome fool!" "Now, don't get excited," laughed Old King Brady. "You must know, sir, that we are engaged upon very important business. Some time ago we saw you come out of that house, and thinking you were a burglar we followed you down to the East river." "You followed me?" gasped Mason, with a guilty start. "Oh, dear, yes. And we saw you meet Sim Johnson on the pier, and we saw you get into the rowboat with your bundle, and we saw the little old man with the gray beard row you out on the stream, and then we saw you all pull up the object you had towing astern, take it into the boat, work over it a while, toss it back, and row away." Mason's face had grown deathly pale.