"That's the strangeness of un," said Lige.
"Let's show un to Doctor Joe," suggested David.
But Doctor Joe, when they broke in upon him a moment later, was as mystified as they.
"It looks," said he, "as though something had been cached and here are the directions for finding the cache. There's a threat in the letter, too, and that looks bad. It's a mystery, lads, we'll try to search out. It doesn't look right. Perhaps it's the clue to some crime."
"How can we search un out?" asked David excitedly. "We're not knowin' the rock, and there's plenty of rocks hereabouts."
"That's true," admitted Doctor Joe. "Go and put the paper back as you found it, and we'll see what we can make out of it later."
The whole camp was excited and every one followed David back to the cairn when he returned to restore the letter to its place in the can.
"'Tis something somebody's tryin' to hide," suggested Peter.
"There's no doubtin' that," said David. "I'm thinkin' 'tis not right whatever 'tis."
"We'll get camp in shape and have our dinner and then try to solve the mystery," said Doctor Joe. "It is a real mystery, for no one would make an ordinary cache in this way, and if it was an honest matter there would be no threat."