They heard a man’s voice in the distance. They could not distinguish what he was saying, for he was still too far away, but gradually the tones grew louder. Then, to their alarm, they heard footsteps. Hastily, they retreated into the secret chamber. “Quick! The door,” snapped Frank. They closed the door quietly. “Now the boxes. If they come in here they’ll notice that the boxes have been moved. Quick.” Swiftly the Hardy boys began to pile the empty boxes back on the platform that projected from the bottom of the door. They worked as quietly as possible and as they worked they heard the footsteps on the stairs drawing closer and closer. Finally, the topmost box was in place. “Out the other door.” They sped across the floor of the chamber toward the door that led to the stairs they had just recently ascended, but hardly had they reached it before they heard a rattle at the latch of the door on the opposite side of the cave. “We haven’t time,” whispered Frank. “Hide.” The beam of the flashlight revealed a number of boxes close by the door. Over these boxes had been thrown a heavy bolt of silk, the folds of which hung down to the floor. They scrambled swiftly in behind the boxes, pressing themselves close against the wall. They did not have more than time to hide themselves and switch out the light before they heard the other door open. “There’s a package of dope in that shipment that came in last night,” they heard a husky voice saying. “We’ll bring it upstairs, for Burke says he can get rid of it for us right away. No use leaving it down here.” “Right,” they heard some one else reply. “Anything else to go up?” “No. We won’t start moving the rest of this until the end of the week. It’s too dangerous. Let Burke take out the shipment he has, along with this dope, and then we’ll lay low for a few days. I’m getting a bit nervous.” “What does the big boss think about it?” “That’s his idea too. Here—wait till I switch on that light.” There was a click, and suddenly the chamber was flooded with light. The cave had been wired for electricity. The Hardy boys crouched in their hiding place. Their hearts were pounding madly. Would they be discovered? Footsteps slowly approached the boxes behind which they were concealed! CHAPTER XVIII A STARTLING DISCOVERY The Hardy boys were tense with a realization of their peril. The strong electric light that hung from the center of the ceiling cast such a vivid illumination that they were sure they would be seen, particularly when they found that the boxes behind which they were hidden were spaced some distance apart. But for the folds of silk that hung down over the opening they would certainly have been seen. “Here’s some of that special silk,” they heard the first man say. “Perhaps I’d better bring it up too. Burke was saying he could handle some more silk.”