It was night, and only a few dim lights here and there in the long, deserted corridors showed them which way to go. They did not know what turns to take. Any moment might send them stumbling upon a band of their enemies.
They conversed in whispers, went a little way down one passage, only to find that it ended against a blank wall, returned to try another with like poor results. They wanted to get out into the open, to find the House on Wheels if possible, and escape in that. But luck seemed to be against them.
They wandered about, several times having to take refuge behind piles of débris to escape groups of men. Presently they saw a light at one end of a long corridor. Stealing toward it, they found that the light came from an open room, whence proceeded the murmur of many voices. Adjoining the large room, in which several men were gathered, was a smaller apartment, a storage place, evidently.
"Come in here!" whispered Tom to his chum, and they slipped in not a second too soon, for Cunningham strode down the hall and entered the main, lighted room where a conference seemed to be going on.
Then, hidden in the small room and listening at a ventilator communicating with the other apartment, Tom and Ned heard enough talk to make clear to them the nature of the business carried on in the old castle.
As Tom had suspected, Cunningham was a rascally but talented manufacturer of fine optical and scientific machines and instruments. He had failed in doing a legitimate business and had turned to crooked ways.
As the talk went on, Tom saw why he had been approached to make machinery and tools for turning out illegal goods. It was because Cunningham wanted to sell them at an enormous profit, not having to pay any patent royalties. Owing to Tom's refusal, and because of his inability to get other firms to make any machines, Cunningham had taken to stealing shipments of goods from large manufacturing concerns. He had allied himself with a band of train robbers who, departing from the usual holding up of pay and express cars, were looting fast freights. Sometimes the trains were held up by means of false signals and again cars on sidings were broken into and the cases stolen and brought to the castle for distribution among fences, as dealers in thieves' loot are called.
Cunningham was doing some manufacturing in the castle, it became known to Tom and Ned as they listened, and this branch would have been gone into on a larger scale had Tom consented to make the necessary machinery.
Then, unexpectedly, the two heard some startling news. Floyd Barton was Cunningham's nephew and the young man who had danced so often with Mary Nestor was using part of his wealth in the illegal manufacture of patented goods. Whether Barton was present at the conference, Tom and Ned could not discover, for though they could hear the talk they could not see the speakers.
"Well, we've found out all we want to know, Ned," remarked Tom, as they got down off the box on which they had been standing to bring their ears nearer the ventilator.