Drummond listened, every nerve a-tingle, even while with hurried hands he cut open the shirt at the brawny throat and felt for fluttering heart-beat or faintest sign of life.  Useless.  The shot-hole under the left eye told plainly that the leaden missile had torn its way through the brain and that death must have been instantaneous.  The soldier’s arms and accoutrements, the horse’s equipments, were gone.  The bodies lay unmutilated.  The story was plain.  Separated in some way from the detachment, Donovan and his companion had probably sighted the signal blazing at the pass and come riding hard to reach the spot, when the unseen foe crouching across their path had suddenly fired the fatal shots.  Now, where was the paymaster?  Where the escort?  Where the men who fed the signal-fire,—­the fire that long before midnight had died utterly away.  Whither should the weary detachment direct its march?  Ceralvo’s lay a dozen miles off to the northwest, Moreno’s perhaps eight or nine to the southeast.  Why had the escaped trooper headed his fleeing steed in that direction?  Had there been pursuit?  Ay, ten minutes’ search over the still and desolate plain revealed the fact that two horsemen lurking in a sand-pit or dry arroyo had pushed forth at top speed and ridden away full tilt across the desert, straight as the crow flies, towards Moreno’s well.  Even while Drummond, holding brief consultation with his sergeant, was deliberating whether to turn thither or to push for the signal-peak and learn what he could from the little squad of blue jackets there on duty, the matter was decided for him.  Sudden and shrill there came the cry from the outskirts of the now dismounted troop clustered about the body of their comrade.

“Another fire, lieutenant!  Look!—­out here towards the Santa Maria.”

The sergeant sprang to his feet, shouldering his burly way through the excited throng.  One moment more and his voice was heard in louder, fiercer tones.

“No signal this time, sir.  By God! they’ve fired Moreno’s ranch!”

III.

Shortly after sunset on this same hot evening the sergeant in charge of the little signal-party at the Picacho came strolling forth from his tent puffing at a battered brier-root pipe.  Southward and a few hundred feet below his perch the Yuma road came twisting through the pass, and then disappeared in the gathering darkness across the desert plain that stretched between them and the distant Santa Maria.  Over to the east the loftiest crags of the Christobal were still faintly tinged by the last touch of departed day.  Southward still, beyond the narrow and tortuous pass, the range rose high and precipitous, covered and fringed with black masses of cedar, stunted pine, and juniper.  North of west, on the line of the now invisible road, and far out towards the Gila, a faint light was just twinkling.  There lay Ceralvo’s, and nowhere else, save where the embers of the cook fire still glowed in a deep crevice among the rocks, was there light of any kind to be seen.  A lonely spot was this in which to spend one’s days, yet the soldier in charge seemed in no wise oppressed with sense of isolation.  It was his comrade, sitting moodily on a convenient rock, elbows on knees and chin deep buried in his brown and hairy hands, who seemed brooding over the desolation of his surroundings.