Now the blanket of rain lifted and shook away to comparative clearness—­lifted, and for the first time he could look far away across the plains.  Nothing but grey, rain-washed desert met his eyes, and then the whistling broke once more upon him at the crest of a thrilling run.  Mac Strann strained his eyes through the mist of the storm and then he saw, vaguely as a phantom, the form of a horseman rushing swiftly into the very teeth of the wind.  The whistle wavered, ended, and in its place the long yell of a wolf cut the air.  Mac Strann brandished a ponderous fist in defiance that was half hysterical.  Man or beast alone he would meet—­but a wolf-man!—­he whirled the horse again and urged him heedlessly into the water.

The whirlpool no longer opened before him—­it had passed on down the arroyo and left in its wake a comparative calm.  So that when the horse took the water he made good progress for some distance, until Mac Strann could see, clearly, the farther bank of the stream.  In his joy he shouted to his horse, and swung himself clear from his saddle to lighten the burden.  At the same time they struck a heavier current and it struck them down like a blow from above until the water closed over their heads.

It was only for a moment, however; then they emerged, the horse with courageously pricking ears and snorting nostrils just above the flood.  Mac Strann swung clear, gripping the horn of the saddle with one hand while with the other he hastily divested himself of all superfluous weight.  His slicker went first, ripped away from throat and shoulders and whipped off his body by one tug of the current.  Next he fumbled at his belt and tossed this also, guns and all, away; striking out with his legs and his free arm to aid the progress that now forged ahead with noticeable speed.

The current, to be sure, was carrying them farther down the stream, but they were now almost to the centre of the arroyo and, though the water boiled furiously over the back of the horse, they forged steadily close and closer to the safe shore.

It was chance that defeated Mac Strann.  It came shooting down the river and he saw it only an instant too late—­a log whipping through the surface of the stream as though impelled by a living force.  And with arrowy straightness it lunged at them.  Mac Strann heaved himself high—­he screamed at the horse as though the poor brute could understand his warning, and then the tree-trunk was upon them.  Fair and square it struck the head of the horse with a thud audible even through the rushing of the stream.  The horse went down like lead, and Mac Strann was dragged down beneath the surface.

He came up fighting grimly and hopelessly for life.  For he was in the very centre of the stream, now, and the current swept him relentlessly down.  There seemed to be hands in the middle of the arroyo, and when he strove to battle his way to the edge of the water the current tangled at his legs and pulled him back.  Yet even then he did not fear.  It was death, he knew, but at least it was death fighting against a force of nature rather than destruction at the hands of some weird and unhuman agency.  His arms began to grow numb.  He raised his head to pick out the nearest point on the shore and make his last struggle for life.