tried again. The flame licked at the heavy cord, weakening it strand by strand.
"Look out, Frank," warned Joe.
Frank scrambled back to the corner.
He was just in time. Heavy footsteps in the passage announced the approach of their guard, who came to the entrance, looked at them sullenly for a moment, then turned away again. He went back to the outer cave.
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 re-
