His horse came to a sudden halt, sliding on all four feet and driving up a rush of dirty water before him; even then he had stopped barely in time, for his forefeet were buried to the knees in water.  Before Mac Strann lay a wide arroyo.  In ordinary weather it was dry as all the desert around, but now it had cupped the water from miles around and ran bank full, a roaring torrent.  On its surface the rain beat with a continual crashing, like axes falling on brittle glass; and the downpour was now so fearful that Mac Strann, for all his peering, could not look to the other side.

He judged the current to see if he might swim his horse across.  But even while he stared the stump of a cottonwood went whirling down the stream, struck a rock, perhaps, on the bottom, flung its entire bulk out of the water with the impact, and then floundered back into the stream again and whirled instantly out of sight in the sheeted rain.

No horse in the world could live through such a current.  But the arroyo might turn.  He swung his horse and spurred desperately along the bank, keeping his eye upon the bank.  No, the stream cut back in a sharp curve and headed him farther and farther in the direction of the pursuer.  He brought the mighty horse to another sliding halt and swung about in the opposite direction, for surely there must lie the point of escape.  Desperately he rode, for the detour had cost him priceless time, yet it might be made up.  Ay, the stream sloped sharply into the direction in which he wished to ride.  For a distance he could not judge, since seconds were longer than minutes to Mac Strann now.

And then—­the edge of the stream curved back again.  He thought it must be a short twist in the line of the arroyo, but following it a little further he came to realise the truth.  The arroyo described a wide curve, and a sharp one, and to ride down its banks on either side was merely to throw himself into the arms of Whistling Dan.

Once he struck his fleshy forehead, and then turned with gritting teeth and galloped back for the point at which he had first arrived.  To his maddened brain it occurred that the current of the arroyo might by this have somewhat abated.  He might now make his way across it.  So he halted once more on the bank at the point where the stream doubled back on its course and once more, in an agony, studied the force of the current.  It seemed so placid at the first glance that he was on the verge of spurring the horse into the wide, brown stream, but even as he loosened the reins a gap opened in the middle of the water, widened, whirling at the brim, and drew swiftly into a fierce vortex with a black, deep bottom.  Mac Strann tightened his reins again, and then turned his horse, and waited.

Back the veriest coward against the wall and he becomes formidable, and Mac Strann was one who had never feared before either man or beast or the powers of the storm.  Even now he dreaded no reality, but there dwelt in his mind the memory of how Dan Barry had glared at him in the Gilead Saloon, and how a flicker of yellow light had glowed in the man’s eyes—­a strange and phosphorescent glimmer that might be seen in the darkness of night.  When he turned the head of his horse away from the arroyo, he waited as one waits for the coming of a ghost.  There was the same chill tingling in his blood.