"I might as well tell you, young gentlemen, that there was some one prowling about this camp after we all were asleep last night—"

"What!" cried the Pony Riders in sudden surprise.

"Yes, that is true. Thaddeus and myself chased him around for nearly half an hour, but—"

All eyes were now turned on Tad, who was bending over his plate that they might not observe the grin that was spreading over his face despite the lad's effort to keep it down.

"O Tad, tell us all about it," urged Walter Perkins. "What was he, a bold robber or what?"

"I guess he must have been an 'Or What,'" suggested Stacy Brown wisely.

"Don't mind him. He's dreaming still. It's only his appetite that's here at the table. The rest of him is in bed asleep," jeered Ned Rector, with such a funny grimace that the boys laughed.

"Yes," answered Tad, looking up, "we ran around here in our pajamas until we found each other. Then we gave it up and went to bed."

"But who was it?" insisted Walter.

"It was an—"