“Now!” breathed McKay.  The homing pigeon, released, walked nervously out over the wet leaves on the forest floor, and, at a slight motion from the girl, rose into flight.  Then, as it appeared above the trees, there came the cracking report of a shotgun, and they saw the bird collapse in mid-air and sheer downward across the hog-back.  But it did not land there; the marksman had not calculated on those erratic gales from the chasm; and the dead pigeon went whirling down into the viewless gulf amid flying vapours mounting from unseen depths.

Miss Erith and McKay lay very still.  The Hunnish marksman across the hog-back remained erect for a few moments like a man at the traps awaiting another bird.  After awhile he coolly seated himself again under the dripping ledge.

“The swine!” said McKay calmly.  He added:  “Don’t let them cross.”  And he rose and walked swiftly back toward the northern edge of the forest.

From behind a tree he could see two Hun cable-guards, made alert by the shot, standing outside their hut where the cable-machinery was housed.

Evidently the echoes of that shot, racketing and rebounding from rock and ravine, had misled them, for they had their backs turned and were gazing eastward, rifles pointed.

Without time for thought or hesitation, McKay ran out toward them across the deep, wet moss.  One of them heard him too late and McKay’s impact hurled him into the gulf.  Then McKay turned and sprang on the other, and for a minute it was a fight of tigers there on the cable platform until the battered visage of the Boche split with a scream and a crashing blow from McKay’s pistol-butt drove him over the platform’s splintered edge.

And now, panting, bloody, dishevelled, he strained his ears, listening for a shot from the hog-back.  The woods were very silent in their new bath of sunshine.  A little Alpine bird was singing; no other sound broke the silence save the mellow, dripping noise from a million rain-drenched leaves.

McKay cast a rapid, uneasy glance across the chasm.  Then he went into the cable hut.

There were six rifles there in a rack, six wooden bunks, and clothing on pegs—­not military uniforms but the garments of Swiss mountaineers.

Like the three men across the hog-back, and the two whom he had so swiftly slain, the Hun cable-patrol evidently fought shy of the Boche uniform here on the edge of the Forbidden Forest.

Two of the cable-guard lay smashed to a pulp thousands of feet below.  Where was the remainder of the patrol?  Were the men with the shotguns part of it?

McKay stood alone in the silent hut, still breathless from his struggle, striving to think what was now best to do.

And, as he stood there, through the front window of the hut he saw an aviator and another man come down from the crest of Thusis to the chasm’s edge, jump into the car which swung under the cable, and begin to pull themselves across toward the hut where he was standing.