"Yes; I have something that I want you to help me with. Perhaps we may be able to do a great service for our employers. I am not quite sure yet. I can't be until we have tried something." "I'm with you in anything, Steve," answered Bob with emphasis. After supper, that night, the boys went directly to their room, where they were soon lost in earnest conversation. Their conversation was carried on in whispers and the hour was well along toward midnight when they had finished with their plans. "Now what do you think of it?" questioned Steve, as they started to make ready for bed. "If you've struck it right we have stumbled on to the biggest game of crookedness in the mines. I mean _you_ have discovered it; you didn't exactly stumble on the game." "Be very careful. Don't make any mistake. I, on my part, will keep my eyes open if I find I can do so without attracting attention. To-morrow night we will compare notes." "Don't worry about me. I'll have it down pat. All ready to turn in?" "Yes." Bob blew out the light and the boys tumbled into bed, where they were soon fast asleep. CHAPTER XII THE BOYS EXPOSE A PLOT On the following morning, when the lads reported for work, they were full of their new purpose. Each was silent as to what that purpose was, but a close observer would have noticed that the boys were keenly watchful of everything that was going on about them. To all intents Steve was devoting his energies to unloading the dump cars in the shortest possible time, and Bob to filling them again in record time. Up to the noon hour nothing had occurred of interest. The two boys did not meet at the lunch hour, deeming it best not to arouse suspicion by their actions, and thus possibly defeat their purpose. Steve ate his lunch in silence, not once looking toward the scowling Marvin. In fact, Marvin had not caught the boy looking at him during the forenoon. "I think the fun will begin before long," mused Steve, wiping his mouth and moving over to a trickling spring on the other side of the level. "I have prepared the way and now we shall see." A long train of ore cars came in a few moments after the whistle blew, and the tally-man was kept busy plugging the holes in the boards as the cars were called out. So busy was Marvin that he did not get a chance to turn about to look at Steve. Perhaps he would not have done so, at any rate. Steve, however, was looking at the tally-man, watching the latter out of the corners of his eyes. The pegs moved skilfully and quickly from hole to hole on the boards, then the man Marvin sat down while the unloading progressed. Rush had seen that which sent the color to his cheeks, and caused his heart to beat a little faster. His sharp eyes had made a discovery. He was as positive as it was possible to be but there was more to be done before his case was fully made out.