“Aha!” exclaimed Mr. Hardy, in mock surprise. “So my sons were investigating, eh? What was it? A murder? A plot to blow up the White House? A train wreck? Something big, I hope.”

“No⁠—not quite that bad,” admitted Frank. “It was a car theft.”

Mr. Hardy shook his head.

“I’m disappointed in you,” he said solemnly. “I really am. To think that sons of mine should investigate a car theft. I thought you wouldn’t bother about anything less than a murder!” His eyes twinkled, and the Hardy boys, who were accustomed to their father’s good-natured banter, smiled back at him.

“We weren’t just practicing detective work, Dad,” explained Frank. “You see, Chet Morton’s roadster was stolen this morning.”