He felt something else--a stretch of wire fixed in the ground with the far end hanging in the void.

That would be the spy's explanation if anyone heard the sound and came seeking the cause.
Somewhere in the darkness before him and below was the man, not a yard off.

Peter remained very still, studying the situation.

He could not see, but he could feel the presence, and he was trying to decide the relative position of the man and bell and their exact distance from him.

The thing was not so easy as it looked, for if he jumped for where he believed the figure was, he might miss it and get a bullet in the stomach.