The afternoon local pulled into the station, and Fenton Hardy stepped down from the parlor car, bag in hand, light coat over one arm. He was a tall, dark-haired man of about forty years of age. He had a quick, pleasant smile for his sons and he shook hands with them warmly. "How's mother?" he asked, after the first greetings. "She's fine," replied Frank. "She said there'd be something special for supper to-night, seeing you're back." "Good! And what have you two been doing? Kept out of mischief, I hope." "Well, we've kept out of mischief," said Joe; "but we haven't kept out of trouble." "What's the matter?" "We just got fooled by a smart stranger who stepped off the express. It cost us five dollars." "How did that happen?" "He asked us to change a five dollar bill for him--" "Ah, ha!" exclaimed Fenton Hardy, raising his eyebrows. "And what then?" "It was counterfeit." Mr. Hardy looked grave. "Have you got it with you?" "Yes," answered Frank, producing the bill. "I don't think we can be blamed such an awful lot for being fooled. It certainly looks mighty like a good one." Fenton Hardy put down his bag and examined the bill closely for a moment. Then he folded it up and put it in his waistcoat pocket. "I'll take care of this, if you don't mind," he said, picking up his bag and beginning to walk toward the station exit. "As it happens, I know something about this money." "What do you mean, dad?" asked Frank quickly. "I don't mean that I know anything about this particular five dollar bill, but I know something about this counterfeit money in general. As a matter of fact, that is why this trip took me longer than I had thought it would. When I finished the case that originally took me away, the Government called me in on this counterfeit money case." "Is there a lot of it going around?" "Too much. Within the past few weeks the East has been flooded with it, and the circulation seems to be spreading. There seems to be a central counterfeiting plant somewhere, with experts in charge of it, and they are turning out imitation bills so clever that the average person can hardly detect them. The Federal authorities are worrying a great deal about it." "And this is one of the bills?" "It looks just like some of the others that have been turned in, although chiefly they have been dealing in tens and twenties. The man who stepped off the train was probably one of their agents, trying to convert as much of the counterfeit money into good cash as he could. When he saw that you were only boys he thought there would be a better chance of getting change for five dollars than ten. Then, of course, he may only have been some one who had been fooled by the counterfeit and decided to get rid of it by passing it on to some one else." "I wish he had asked us to change one of his counterfeit tens, instead," mourned Joe. "We would have been five dollars to the good." CHAPTER III