"What?" asked Tom, in some surprise.
"Don't destroy that letter. It may give us a clew. Let me have it. I'll put a man at work on that end of this game."
"Bless my checkerboard!" cried Mr. Damon. "This game has so many ends that you don't know where to begin to play it."
The government man smoothed out the crumpled piece of paper, and looked at it carefully, and also gazed at the envelope.
"It's pretty hard to identify plain print, done with a lead pencil," he murmured. "And this didn't came through the mail."
"I wonder how it got here?" mused Ned. "Maybe some of the crowd that was here when we started off dropped it for the smugglers. Maybe the smugglers were in that crowd!"
"Let's take a look outside," suggested Mr. Whitford. "We may be able to pick up a clew there."
Although our friends were tired and sleepy, and hungry as well, they forgot all this in the desire to learn more about the mysterious warning that had come to them during the night. They all went outside, and Ned pointed to where he had picked up the envelope.
"Look all around, and see if you can find anything more," directed the custom agent.
"Footprints won't count," said Tom. "There was a regular circus crowd out here yesterday."