At that instant Tom tripped over a plank and went down full length, making quite a racket.  When he picked himself up he was surprised to see the man he was after dart from inside a big box and start for the fence, near a point where there were some packing-cases piled up, making a good approach to the barrier.  The fugitive had been hiding, waiting for a chance to escape, and Tom’s fall had alarmed him.

“Here!  Hold on there!  Come back!” cried the youth as he recovered his wind and leaped forward.

But the man did not stay.  With a bound he was up on the pile of boxes, and the next moment he was poised on top of the fence.  Before leaping down on the other side, a jump at which even a practiced athlete might well hesitate, the fleeing stranger paused and looked back.  Tom gazed at him and recognized the man in an instant.  He was the third of the mysterious trio whom the lad had seen in the Mansburg restaurant.

“Wait a minute!  What do you want sneaking around here?” shouted Tom as he ran forward.  The man returned no answer, and an instant later disappeared from view on the other side of the fence.

“He jumped down!” thought Tom.  “A big leap, too.  Well, I’ve got to follow.  This is a queer proceeding.  First one, then the second, and now the third of those men seem determined to get something here.  I wonder if this one succeeded?  I’ll soon find out.”

The lad was up on the pile of packing-cases and over the fence in almost record time.  He caught a glimpse of the fugitive running toward the woods.  Then the boy leaped down, jarring himself considerably, and took after the man.

But though Tom was a good runner he was handicapped by the fact that the man had a start of him, and also by the fact that the stranger had had a chance to rest while hiding for the second time in the big box, while Tom had kept on running.  So it is no great cause for wonder that Mr. Swift’s son found himself being distanced.

Once, twice he called on the fleeing one to halt, but the man paid no attention, and did not even turn around.  Then the youth wisely concluded to save his wind for running.  He did his best, but was chagrined to see the man reach the woods ahead of him.

“I’ve lost him now,” thought Tom.  “Well, there’s no help for it.”

Still he did not give up, but kept on through the patch of trees.  On the farther side was Lake Carlopa, a broad and long sheet of water.

“If he doesn’t know the lake’s there,” thought our hero, “he may keep straight on.  The water will be sure to stop him, and I can catch him.  But what will I do with him after I get him?  That’s another question.  I guess I’ve got a right to demand to know what he was doing around our place, though.”

But Tom need not have worried on this score.  He could hear the fugitive ahead of him, and marked his progress by the crackling of the underbrush.

“I’m almost up to him,” exulted the young inventor.  Then, at the same moment, he caught sight of the man running, and a glimpse of the sparkling water of Lake Carlopa.  “I’ve got him!  I’ve got him!” Tom almost cried aloud in his excitement.  “Unless he takes to the water and swims for it, I’ve got him!”