said Dick, cautiously. "If they have gone into the second room down there maybe we can make them prisoners!"
"That's the idea!" cried Sam. "Just the thing!"
"Hush, Sam, or you'll spoil all."
Scarcely daring to breathe, now that they knew the strange men were so close, the three Rover boys walked to the open doorway of the old mill and went inside. Dick led the way and crossed to where an enclosed stairs ran to the floor below. On tiptoes he went down, not trusting a step until he was sure of his footing. It was well he did this, for two of the steps were entirely rotted away, and he had to warn his brothers, otherwise one or another might have had a fall.
Standing in the wheel room of the old mill the boys saw another streak of light, coming from the room which Dick had suggested. The door to this was closed, a bolt on the inner side holding it in place. There was another bolt on the outside, which Dick remembered having seen on a previous visit.
"We can lock them in if we wish," he whispered.
"Do it," answered his brothers promptly. The bolt was large and old-fashioned, and Dick had considerable trouble in moving it into its
