At that moment there was an interruption. A shout from the mill attracted their attention and, looking up, they saw Uncle Dock standing in the doorway. "Lester!" he bellowed angrily. "Yes?" "Come up here this minute," ordered the old man. He left the door and came down the slope toward the river. "Now I'm in for it," said the boy. "I suppose he'll be angry now because I was talking to you." Uncle Dock was indeed angry. As he came up to the group he was muttering beneath his breath. "Get back up to the mill, you young rascal!" he ordered, giving Lester a cuff on the side of the head. "How often have I told you not to be talking to strangers. You talk too much altogether. Get back up to the mill and stay there." "We were just chatting--" began the boy, but Uncle Dock silenced him with a blow. With an appealing glance at the Hardy boys, Lester began to make his way back up the slope toward the mill. Uncle Dock turned toward Joe and Frank, surveying them resentfully. "What are you doing, loafing around here?" he demanded. "We're not loafing. We have been fishing in the river," said Frank. "Not that it's any of your business, so far as I can see." "I'll make it my business," thundered Uncle Dock. "You two fellows had better stay away from here after this. We don't want you hanging around here." "The river is free," Joe reminded him. "Keep away from around this mill or I'll make it hot for you. What was that rascal of a boy telling you?" "We were just talking," replied Frank evasively. "Well, don't talk to him again. I don't want him mixing up with all the riff-raff of the country and talking to every Tom, Dick and Harry that comes around. I'll thank you to stay away from here after this." Whereupon Uncle Dock, still grumbling indignantly, went stamping up the slope again toward the mill. The Hardy boys, not a bit alarmed by the outburst, but feeling that they had gained valuable information that day, began to move slowly down the river bank away from the vicinity of the old mill. CHAPTER XVIII SUSPICIONS "What do you think, Joe?" asked Frank, as they were speeding back to Bayport on their motorcycles. "I don't think Uncle Dock is a scientist any more than I am." "That's my opinion, too. Why should they have so much secrecy about a new kind of breakfast food? Why won't they even let Lester into the workroom with them?" "Something fishy about it. And it's plain by now that Uncle Dock doesn't like strangers around the place." "That poor kid must lead a lonely life with that gang. It's a wonder he doesn't run away from them." "He has no place else to go, I suppose. He seems a nice sort of chap, too," Joe answered. "Well, we didn't get anything definite from him, but we know enough to make us mighty suspicious of what's going on in that old mill." "I'd just like to get a look at that machinery in the secret room the boy mentioned." Frank was silent for a while.