As they loped across the wide stretch of desert flats that reached to the sand hills, shutting the ranch from sight, the twilight fell, and with it came sharp gusts of wind that now and then brought a whirl of desert dust. Harder and harder it blew. Nearer and nearer--then it fell upon them in its malevolence, to catch them--to hold them in its uncanny clasp an instant--and then, releasing them, go madly racing off to the farther twilight, moaning in undertone as it went. Then heat lightning struck vividly at the horizon, and the air everywhere became surcharged with the electric current of a desert sand storm. They heard its roar coming up the valley. Audrey Glendower felt her nerves a-tingle. This, too, was an experience! In sheer delight she laughed aloud at the excitement showing in the quivering horses--their ears nervously pointing forward, and their nostrils distended, as with long, eager strides they pounded away over the wind-beaten levels. Then the storm caught them at its wildest. Suddenly a tumble-weed, dry and uprooted from its slight moorings somewhere away on the far side of the flats, came whirling toward them broadside in the vortex of a mad rush of wind in which--without warning--they were in an instant enveloped. As the great, rolling, ball-like weed struck her horse, Miss Glendower took a tighter grip on the reins and steadied herself for the runaway rush into the dust storm and the darkness. The wild wind caught her, shrieked in her ears, tore at her habit as though to wrest it from her body, dragged at the braids of heavy hair until--loosened--the strands whipped about her head, a tangled mass of stinging lashes.