“I suppose you think Sid Merrick’s doings are a joke, too,” said Sam, before he had time to think twice.

“Ha! what do you know of Merrick?” ejaculated Cuffer.  “They must have been listening to our talk,” he added, in a low tone to his companion.

“Yes, and if so, we are in a bad box,” answered Shelley.  “I’d give a good deal to be out of here just now.”

“Talk to them, while I take a look around,” continued Cuffer, struck by a sudden idea.

Shelley did as told, pleading with the three Rovers to let him go and offering to pay fifty dollars for his liberty.  He talked in a loud tone, to cover up what noise his companion might make.  The boys listened, but refused to open the door until some sort of help should arrive, or until morning came.

“Sam, you go outside and see if Jack and the Ditwolds are anywhere around,” said Dick, and the youngest Rover departed immediately.

Presently Tom and Dick heard Cuffer give a cry of pain.

“You’ve stepped on my sore toe!” howled the man.  “Phew! how it hurts!”

The two men talked about the hurt toe for several minutes.  Then their voices suddenly ceased.  Tom and Dick strained their ears, but could hear absolutely nothing.

“They must be up to some trick,” whispered the eldest Rover.  “Hi, you, what are you doing?” he called out.

There was no answer and the silence was just as ominous as before.  The light in the inner room had gone out.

“What are you doing?” repeated Dick, and ran close to the door to listen.  Nothing but absolute silence followed.

What to do next the two boys did not know.  They waited for fully five minutes—­then five more.  Presently they heard Sam coming back.

“I yelled for Jack and the others, but I got no answer,” said he.  “What are the men doing?”

“We don’t know,” answered Tom.  “We are afraid they are up to some trick.”

“A trick?” repeated Sam.  Then he gave a gasp.  “The room—­isn’t there a back door, leading out to the shed?”

“I don’t know,” answered Dick.

“I’ll run and see.”

Sam was gone less than two minutes when they heard a cry, and then he pounded on the door they had so carefully guarded.

“There is a back door and it is wide open.  The men have gone!” was his dismaying announcement.

CHAPTER VI

THE STORY OF A TREASURE

It was a disheartening discovery, but the three Rover boys did not stop to think it over.  Throwing open the bolted door, Tom and Dick joined Sam, and in the darkness made their way to the rear of the room in which they had held Cuffer and Shelley prisoners.  In a minute more they were outside, under the trees at the rear of the old mill.

“Which way did they go?”

Tom asked the question, but nobody could answer it.  The moon had now gone under some clouds and it was so dark they could scarcely see ten feet in any direction.