“Ah, that explains it,” said Chick, smiling. “I wondered at what you were driving.” “Gee! I was in on that, all right,” put in Patsy. “I couldn’t fathom it.” “I suspected that they were the finger prints of the girl who sweeps and dusts the room,” Nick continued. “That would have given her an opportunity, or many of them, in fact, to stealthily examine the inventory, and even make a copy of it.” “Surely,” Chick nodded. “I decided, however, that I had better clinch my suspicion. I found the same dainty finger print on the damp silver spoon which I had her bring and hold for a moment.” “Gosh, that did settle it!” said Patsy. “Clever work, chief, all right.” “I am convinced of the guilt of this girl and the part she has played in the robbery.” “Why didn’t you arrest her, then, and force a confession from her?” Chick inquired. “That last might not be easily done,” Nick replied. “Furthermore, the girl may not know the crooks.” “Not know them? How can that be, providing your suspicions are correct?” “She may have been lured into this by a supposed friend, one who is in league with the crooks and who is acting as a sort of go-between.” “I see the point,” bowed Chick. “Minerva Grand might not be able to put us on the track of the gang itself.” “That’s the point precisely,” said Nick. “I would not take the chance of arresting her, therefore, or even of letting her know that I suspect her. That is why I did not make a special mark of her in my inquiries, also why I have kept all this from the Waldmeres and left them entirely in the dark. I feared they might betray me to the girl by some word, or look.” “I see.” “Now, to go a step further, the man who held up McLauren was one of the gang,” Nick continued. “He was, in reality, the chief of the gang. He is the same man who followed Frank Gilbert to Boston, and who so artfully had the three cases put near the door of the freight car, and afterward succeeded in getting a forged copy of the bill of lading. He is a keen and clever rascal. He is all the mustard in the pot, that fellow.” “You speak as if you already know him,” said Chick, gazing. “I do know him, Chick.” “The dickens! Whom do you suspect?” “A man who stopped me in Madison Avenue a few days ago,” Nick declared, with more feeling. “It was the first time I have seen him for a couple of years. He cursed me for having put him to the bad, and he threatened me with something no less strange than--the melting pot.” “The melting pot?” Chick echoed perplexedly. “What did he mean?” “That’s right, too. What?” questioned Patsy. Nick Carter laughed a bit grimly. “I did not know what he meant at the time, nor seriously care,” he replied, after a moment. “I now know, however, what he meant by the melting pot. He threatened to put something over on me and send me all to the bad. It now is plain enough to me that he had this robbery in mind, and the job well in hand.” “You mean?”