"I have forgotten some papers!" he exclaimed, not turning his head. "I must have left them on the bank where we ate lunch. I'll get them. Don't wait for me. I can find my way back."
Then he was gone, a curve in the road hiding him from sight. But by this time Frank had come up to his chums. He saw Mr. Hardman's sudden retreat, and had caught the words the man called back to the boys. At the sound of them Frank broke into a run.
"What's the matter?" cried Bart, surprised at his friend's action.
"I must catch that man!" exclaimed Frank, as he raced past his chums.
For a moment the three boys were so surprised they did not know what to make of it. The queer action of Mr. Hardman, in suddenly fleeing, was only equaled by Frank's pursuit.
"Let's go and see what it means," suggested Ned, as he turned to go back over the road.
The sun had gone under a cloud and the woods were quite dark, as the forest was dense at this point. The three chums hurried on in the semi-twilight. They had not gone far before they met Frank coming back.
"Did you catch him?" asked Ned.
"No. He must have turned off into the woods. What is his name? How did you fellows come to be out with him? What made him run back as soon as he saw me?"
"One at a time," suggested Ned. "We can't answer all those questions at once. What made you run after him?"