Red Lake must be his Rubicon. Either he must enter the unknown to seek, to strive, to find, or turn back and fail and never know and be always haunted. A friend's strange story had prompted his singular journey; a beautiful rainbow with its mystery and promise had decided him. Once in his life he had answered a wild call to the kingdom of adventure within him, and once in his life he had been happy. But here in the horizon-wide face of that up-flung and cloven desert he grew cold; he faltered even while he felt more fatally drawn. As if impelled Shefford started his horse down the sandy trail, but he checked his former far-reaching gaze. It was the month of April, and the waning sun lost heat and brightness. Long shadows crept down the slope ahead of him and the scant sage deepened its gray. He watched the lizards shoot like brown streaks across the sand, leaving their slender tracks; he heard the rustle of pack-rats as they darted into their brushy homes; the whir of a low-sailing hawk startled his horse. Like ocean waves the slope rose and fell, its hollows choked with sand, its ridge-tops showing scantier growth of sage and grass and weed. The last ridge was a sand-dune, beautifully ribbed and scalloped and lined by the wind, and from its knife-sharp crest a thin wavering sheet of sand blew, almost like smoke. Shefford wondered why the sand looked red at a distance, for here it seemed almost white. It rippled everywhere, clean and glistening, always leading down. Suddenly Shefford became aware of a house looming out of the bareness of the slope. It dominated that long white incline. Grim, lonely, forbidding, how strangely it harmonized with the surroundings! The structure was octagon-shaped, built of uncut stone, and resembled a fort. There was no door on the sides exposed to Shefford's gaze, but small apertures two-thirds the way up probably served as windows and port-holes. The roof appeared to be made of poles covered with red earth.