Again the young detective’s speculations were interrupted, however; this time in a different, and, at first, more puzzling way.
The air suddenly became still closer and more oppressive, as if they had been shut in a confined space; but that was not all.
The sound of shoveling began at once, and lumps of something hard struck and rolled, with a hollow sound, just above Patsy’s head.
What was happening?
Nick’s assistant did not take long to penetrate the mystery, although he had only his ears to aid him.
He concluded that a wooden cover had been placed over their place of confinement, and that coal was being shoveled in on top of it. They were probably in an old coal bin, he reasoned, with a false bottom, and when the space above was filled, there would be nothing to indicate that the whole bin was not full of coal.
It was a clever arrangement—altogether too clever for comfort. Nick and his assistants had encountered its like more than once, and it could not have deceived them for long; it might easily prove too much for the police, however, even if they made an investigation.
Nick’s other assistants could be counted on to solve the problem when they finally obtained access to the house—if they could—but it would probably be too late then. Much too late, in fact.
The hole into which the prisoners had been thrown could hardly be more than eight feet square, if that much, and it was not likely that it was more than four feet deep.
It was closed at the top now, and the sides were doubtless fairly tight, in order that no cracks of any size should reveal the hollow space behind.