Hardly had he disappeared when Frank was back at the candle. He thrust the rope into the flame again.
When he could stand the burning heat no longer he withdrew and tried to break his bonds by sheer force. But, although the ropes had been weakened, they refused to break. He returned to the flame again, and on the next attempt he was successful. So many strands had been burned through that the cords snapped, and his hands were free.
Quickly, Frank went over to his brother. First of all, he took the revolver from Joe's pocket and put it on the rock beside him, in readiness. Then he knelt down and tugged at the strong ropes that bound Joe's wrists so tightly.
The knots were stubborn, but he finally undid them. The ropes fell apart and Joe was free.
"Now!" gritted Frank, picking up the revolver. "We'll go and attend to our friend in the cave."
"Hadn't we better wait here for him? There may be some one with him."
"I guess you're right. We'll take him by surprise the next time he comes back."
Frank went over to the side of the tunnel that led out into the main cave.
"Bring those ropes with you, Joe. Take the other side."
Joe picked up the cords that had bound his own wrists, and took up his position at the other side of the entrance. There the boys waited.