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 socket.  It made a rasping sound, but this was not noticed by the two men, who were conversing earnestly.

“Well, we made a mess of it,” growled the man called Shelley.

“So we did.  But I didn’t think that hired man would wake up.  Neither of us made a bit of noise.  He must be a light sleeper.”

“I only hope they think we were after chickens, Cuffer.  If they knew the truth—­” The man named Shelley broke off with a coarse laugh.

“Well, we got chickens the other night, didn’t we?” and now the man called Cuffer laughed also.  “But say, this is getting serious,” he went on presently.  “Merrick expects us to do this job for him and do it quick, and he won’t like it at all when he finds out how we have missed it.”

“We can’t do the impossible.  Those Rovers are too wide awake for us.”

“They certainly were too wide awake for Merrick in that traction company bond matter.  He was a chump not to sell those bonds as soon as he got hold of them.”

“He didn’t dare—­he was afraid the market was being watched.”

“What does he want of those papers, anyway?”

“I don’t know exactly.  But you know what he said—­there would be a small fortune in it for us if we got ’em.  He says he’s got some papers —­or a map I guess it is—­but he wants these papers, too.  He didn’t dare show himself around here—­you know the reason why.”

“Sure—­those Rovers would recognize him, even if he tried to disguise himself.”

Dick, Tom and Sam listened to this conversation with keenest interest and amazement.  These men had mentioned the name of Sid Merrick, the rascal who had in the past tried so hard to harm them and who had up to the present time escaped the clutches of the law.  Evidently they were in league with Merrick and under his directions.

“We must capture those fellows by all means,” whispered Tom, excitedly.  “If we do, maybe we can find out where Merrick is.”