Something told him, however, that this was no ordinary schoolboy prank. The incident of the fallen ceiling had unnerved him slightly. It was only by good luck that none of them had been seriously hurt. Of course, it may have been entirely accidental, but it seemed to have happened at a strangely opportune time. Then the recollection of the shrieks and the mocking laugh came back to him again and he shivered as he recalled the maniacal intensity of the tones.
"If it was any fellow like ourselves he was a mighty good actor," Frank said to himself. "I've heard of a person's blood running cold, but I never knew what it meant until I heard those yells."
Suddenly his motorcycle began, as he termed it, "acting up." It coughed, lurched, backfired explosively, and then the engine died.
"What a fine time for a breakdown," Frank said, as he dismounted.
Joe drew up alongside. "What's the matter?" he called.
"Engine broke down."
"Gosh, aren't you lucky!" exclaimed Joe, grinning. "There's a shed over at the side of the road. Bring it over under cover."
He pointed to a tumble-down shed near by. Frank realized that it might take some time to discover the trouble, so he trundled the motor-
