It was a curious place in which young Benson lay, a place with a strange history.
Years before a tunnel had been bored into the side of a hill. After the tunnel had been lined with a masonry of stone it was not more than three feet in diameter. This tunnel led into an artificial cave some eighteen feet square and nine feet high. This cave had been shored up and boarded as to ceiling, floor and walls.
A great deal of labor had been expended in building this curious place under a low hill. Yet the original builders had figured that their time so spent would yield large returns. This part of the Florida coast lay conveniently near to Cuba. On moonless nights a small sailing craft would put in along the coast, laden with smuggled Havana cigars. There being no safe place along the shore in which to store the cigars, this place, hidden well in a forest, had been constructed as a safe depository. For some time the cigar smugglers had prospered. Then, as was to have been expected, Uncle Sam's sharp eyed customs men ran the illegal business down, arresting the smugglers, all of whom were subsequently imprisoned.
For a while afterwards this cave had been visited by the curious. All this smuggling, however, was now a thing of many years past, and curiosity-seekers had come to leave the place alone.
M. Lemaire, however, in studying the surrounding country, had heard of the artificial cave. He visited it. At need, he saw that it would suit his purposes. And now Jack Benson lay there, having been brought hither in Mlle. Nadiboff's automobile.
The young submarine captain was now not gagged. He had yelled for help perhaps two hundred times in the long hours since his enemies had left him there. Yet there had been no response. Benson was now willing to believe that there was now no likelihood whatever of his being able to summon help.
Unable to consult his watch, and lying there in complete darkness, the submarine boy had lost track of time. It was now nearly two in the morning. He had not eaten since early the morning before. He was famished, and, what was much worse, was parched for want of a drink of water.
"I wonder if they intend to leave me here to die?" thought Jack Benson, for perhaps the five-hundredth time. "It would be fiendish. Yet looking for mercy in Lemaire would be like looking for a lake of pure water in the Sahara."
Jack shifted, as much as the chain at ankle would permit. He groaned with the discomfort of it all.
As if in answer there came another groan, low, hollow, yet unmistakable. Captain Jack raised himself on one elbow, listening keenly. The groan was repeated.