had to lie there in silence, not daring even to encourage the lads by a whisper. The silence was broken only by the heavy breathing of the two boys, by the scarcely audible sound of the knife against the ropes.
At last the knife cut through one of the ropes and Fenton Hardy's feet were free. Frank pulled the ropes away, but a loose end fell on the floor with a light sound.
Slight as the noise was, it seemed to them almost deafening, in view of the necessity for silence. Desperately, Frank prepared to set to work to cut through the ropes that bound Fenton Hardy's arms. And, even as he reached over with the knife, they heard a sound that sent a thrill of terror through them.
It was a heavy footstep beyond the door through which the smugglers had recently disappeared!
Some one was approaching the underground room.
Frank strained at the knife, but the ropes were stubborn. The dull blade made little impression at first. But at last the rope began to give, and finally, as Fenton Hardy gave a mighty effort, it snapped, and the detective was free.
But the footsteps on the stairs had drawn nearer and it was followed by others. The smugglers were returning.
