The thing that worried Duane was the fact of the bonfires.

He had gathered from the words of one of his pursuers that the brake was a kind of trap, and he began to believe there was only one way out of it, and that was along the bank where he had entered, and where obviously all night long his pursuers had kept fires burning.

Further conjecture on this point, however, was interrupted by a crashing in the willows and the rapid patter of feet.
Underneath Duane lay a gray, foggy obscurity.

He could not see the ground, nor any object but the black trunk of the tree.

Sight would not be needed to tell him when the pack arrived.