For three days the journey continued without a mishap along the shore of Lake Athabasca.  On the fourth night McGill pitched his tent in a clump of banskian pine a hundred yards back from the water.  All that day the wind had come steadily from behind them, and for at least a half of the day the professor had been watching Kazan closely.  From the west there had now and then come a scent that stirred him uneasily.  Since noon he had sniffed that wind.  Twice McGill had heard him growling deep in his throat, and once, when the scent had come stronger than usual, he had bared his fangs, and the bristles stood up along his spine.  For an hour after striking camp the little professor did not build a fire, but sat looking up the shore of the lake through his hunting glass.  It was dusk when he returned to where he had put up his tent and chained the dogs.  For a few moments he stood unobserved, looking at the wolf-dog.  Kazan was still uneasy.  He lay facing the west.  McGill made note of this, for the big Dane lay behind Kazan—­to the east.  Under ordinary conditions Kazan would have faced him.  He was sure now that there was something in the west wind.  A little shiver ran up his back as he thought of what it might be.

Behind a rock he built a very small fire, and prepared supper.  After this he went into the tent, and when he came out he carried a blanket under his arm.  He chuckled as he stood for a moment over Kazan.

“We’re not going to sleep in there to-night, old hoy,” he said.  “I don’t like what you’ve found in the west wind.  It may he a—­thunder-storm!” He laughed at his joke, and buried himself in a clump of stunted banskians thirty paces from the tent.  Here he rolled himself in his blanket, and went to sleep.

It was a quiet starlit night, and hours afterward Kazan dropped his nose between his forepaws and drowsed.  It was the snap of a twig that roused him.  The sound did not awaken the sluggish Dane but instantly Kazan’s head was alert, his keen nostrils sniffing the air.  What he had smelled all day was heavy about him now.  He lay still and quivering.  Slowly, from out of the banskians behind the tent, there came a figure.  It was not the little professor.  It approached cautiously, with lowered head and hunched shoulders, and the starlight revealed the murderous face of Sandy McTrigger.  Kazan crouched low.  He laid his head flat between his forepaws.  His long fangs gleamed.  But he made no sound that betrayed his concealment under a thick banskian shrub.  Step by step Sandy approached, and at last he reached the flap of the tent.  He did not carry a club or a whip in his hand now.  In the place of either of those was the glitter of steel.  At the door to the tent he paused, and peered in, his back to Kazan.