Before they reached the store they heard the shriek of the whistle and the clanging of the bell that indicated that the express was resuming its southward journey. "Our friend can travel in peace," remarked Frank. "He got his five changed anyway." "And the other fellow got his dollar. Everybody's happy." They reached the store and paused outside the entrance to examine an assortment of baseball bats, discussing the relative merits and weights of each, then poked around in a tray of mitts, trying them on and agreeing that none equaled the worn and battered mitts they had at home. Finally they entered the shop, where they were greeted by the proprietor, a chubby and genial man named Moss. Mr. Moss was sitting on the counter reading a newspaper, for business was dull that afternoon, but he cast the sheet aside when they came in. "Looking for clues?" he asked humorously, as they came in. As sons of Fenton Hardy, and as amateur detectives of some ability in their own right, the boys were frequently the butt of jesting remarks concerning their hobby, but they invariably took them in the spirit of good-natured raillery in which they were meant. "No clues here," continued Mr. Moss. "You won't find a single, solitary clue in the place. I had a crate of awfully nice bank robbery clues in yesterday, but they've all been snapped up. I expect some nice murder clues in to-morrow morning, if you'd care to wait that long. Or perhaps you'd like me to order you a few kidnapping clues. Size eight and a half, guaranteed not to wear, tear or tarnish." Mr. Moss rattled on, with an air of great gravity, burst into a roar of laughter at his own joke, then swung his feet against the side of the counter. "Well, boys, what'll it be?" he asked, rubbing his eyes, as the two brothers grinned at him. "What can I do for you?" "We want some pie-plates," said Joe. "Three." "Small ones, I suppose," said Mr. Moss, then chuckled hugely as the boys looked at him in indignation. "I should say not," returned Frank. "The biggest you've got." Mr. Moss laughed very much at this also, and swung himself down from the counter and went in search of the pie-plates. He returned eventually with three that seemed to be of the required size and quality. "Wrap 'em up," said Frank, throwing the five dollar bill on the counter. Mr. Moss wrapped up the plates, then picked up the bill and went over to the cash register. He rang up the amount of the sale and was about to put the money in the till when he suddenly hesitated, then held the bill up to the light. Slowly, he came back to the counter, rubbing the bill between thumb and forefinger, feeling its texture and minutely examining the surface. "Where did you get this bill, boys?" he asked seriously. "We just changed it for a stranger on the train," answered Frank. "What's the matter with it?" "Looks bad to me," replied Mr. Moss dubiously. "I'm afraid I can't take a chance on it."