The little marshal of Haskell had the reputation of being as quick of wit as of trigger finger. Startled as he was by that sudden apparition appearing before them in the dark road, and at being addressed by a woman's voice, the mention of the name Cassady gave him an instant clue. There was but one Cassady in camp, and that individual's reputation was scarcely of a kind to recommend him in the eyes of the law. If any woman sought that fellow in this out-of-the-way spot, it was surely for no good purpose. Brennan caught his breath, these thoughts flashing through his brain. He leaned forward over his saddle horn, lowering his voice confidentially, and managing to achieve a highly meritorious brogue.

"Sure, Oi'm Cassady," he admitted grouchily. "How iver come yer ter guess thot?"

"I was sent here to meet you," she explained hurriedly, as though eager to have her task done. "I thought maybe it wasn't you, with another man along. Who is he?"

"His noime's Crowley; just a friend o' moine; mebbe yer know the lad?"

"No; certainly not. Does he go along with you?"

"Fer only a bit o' ther way"; he lowered his voice to even greater intimacy. "Shure, it's a parfectly still tongue the b'y has in the cheek o' him."

She laughed nervously.

"Well, I'm glad of that; and we'll not stand here discussing the matter. Do you know who I am?"

"Divil a thought have Oi."

"You were expecting to meet Mr. Enright, weren't you? That was what
Bill Lacy told you. He was to explain to you just what you were to do."

Brennan mumbled something indistinctly, now thoroughly aroused to the situation.

"Well, Mr. Enright couldn't come, and Lacy is over across the creek yet, hunting down Ned Beaton's murderer. I am Miss La Rue," she hurried on, almost breathlessly, "and I've brought you Lacy's note, which you are to give to that Mexican—Pasqual Mendez. You understand? You are to give it to him, and no one else. Lacy said you could kill your horse, if necessary, but the note must be there by daylight to-morrow. Here—take it."

Brennan thrust it into an inner pocket, and cleared his throat. There was no small risk in asking questions, yet, unless he learned more, this information might prove utterly useless. The note to Mendez meant little until he discovered where that bandit was to be found. He felt his flesh prickle in the intensity of his suppressed excitement.

"Shure now, miss," he said insinuatingly. "Mr. Lacy must hev' sint more insthructions 'long with ye then them. All ther word thet iver come ter me wus ter saddle oop, ride down here an' mate this man Enright. I don't aven know fer shure whar ol' Mendez is—likely 'nough he be in Mexico."

"In Mexico!" indignantly. "Of course not. Lacy said you knew the trail. It's a place they call 'Sunken Valley'—out there somewhere," and Brennan could barely distinguish the movement of her arm desert-ward. "It's across that sand flat."

"Shoshone?"

"Yes; I couldn't remember the name. That's all I know about it, only
Lacy said you'd been there before."

"Shure, miss," assured the marshal softly, clearly realising that he had already gone the limit, and that any further questioning must lead inevitably to trouble. "If it is Sunken Valley I'm ter ride ter, thet's aisy."

"Then it's good night."

She vanished up the side-trail, as though the wind had blown away a shadow. Except for the slight rustling of dried leaves under her feet, the two men, staring blindly through the darkness, could not have told the direction in which she had gone. Then all was silence, the mystery of night. Brennan gathered up his reins, straightening his body in the saddle. He glanced back toward the dim shade of his companion, chuckling.

"Some bit of luck that, Jim."

"Doesn't seem to me we know much more than we did before," Westcott answered gloomily. "Only that this chap Mendez is at a place called Sunken Valley. I never heard of it; did you?"

"No; I reckon it's no spot the law has ever had any use for. I've supposed all along them Mexican cattle thieves had a hidden corral somewhar in this country; but nobody has ever found it yet. Right now, thanks to this Miss La Rue, I've got a hunch that we're goin' to make the discovery, and put Bill Lacy and ol' Mendez out of business. But there's no sense of our gassin' here. We got a right smart bit o' ridin' to do afore daylight."

They advanced cautiously as far as the bridge, but at that point Brennan turned his pony's head southward, and spurred the reluctant animal up the steep bank. Without question Westcott followed, and the two horses broke into a trot as soon as they attained the more level land beyond. They were slightly above the town now, and could gaze back at the glittering lights in the valley below. The sound of men's voices failed to reach them over the soft pounding of the ponies' hoofs on the prairie sod, but suddenly the distant crackling of a half dozen shots pierced the silence, and their eyes caught the sparkle of the discharges, winking like fireflies in the night. Before they could draw up their mounts, the fusillade had ended, and all beneath them was unbroken gloom.

"Must be rushing the rock," commented Westcott.

"More likely saw something and blazed away at it, just as they did at that log," and Brennan laughed. "Anyhow they haven't discovered we have vanished yet. With an hour more we'll be where trails are unknown."

"In the desert?"

"That is the only safe hiding place around here. Besides we're carrying a message to Mendez."

"Without the slightest knowledge of where that party is."

"Well, hardly that, Jim. I may not know exactly, but I've got a glimmer of a notion about where the cuss hangs out, an' I'm going to have a hunt for it. There's five thousand dollars posted down in Arizona for that fellow, dead or alive; an' I need the money. Besides, I reckon this yere Miss Donovan, an' yer ol' partner—what's his name?—sure, Cavendish—will be mighty glad to see us. You're game for a try, ain't yer?"

"I shall never stop until I do find them, Dan," said the other earnestly, the very tone of his voice carrying conviction. "Every cent of reward is yours; it will be satisfaction enough for me to know those two are safe."

"That's how I figured it. Now let's trot on; we ain't gaining nothing by sittin' our saddles here. We can talk while we travel."

There was a few moments of silence, both men evidently busied with their thoughts; then Westcott asked:

"What is your idea, Dan?"

The marshal rode steadily, humped up over his saddle-horn, his eyes on the uncertainties in front.

"I ain't really got none," he admitted doggedly, "less it be a blind trust in Divine Providence; still I got a medium strong grip on a few things. That Capley girl told you that Matt Moore drove out on the ridge road?"

"Yes; I asked her about that twice."

"Well, he likely was headed for this yere Sunken Valley. That's point number one. But he never followed the ridge road very far, for it skirts the desert. He must have turned off south—but where?"

"Near the lone cottonwood is my guess."

"Why?"

"Because there is a swale there of hard sand, which is easily followed, and leaves no trail. On either side for miles the sand is in drifts, and no two horses would ever pull a wagon through it. This hard ridge, which is more rock than sand, goes straight south to Badger Springs, the only place to get water. I was there once, three years ago."

"You've hit it, old man," exclaimed the other confidently. "That's exactly how I had it doped out. He'd have to use that swale, or go ten miles farther east. I never was at Badger myself, but I've travelled that ridge road some, with my eyes open. Then, I take it, that our course is already laid out pretty straight as far as them springs. Beyond there the general lay of the land may help us, and I aim to reach that point along about daylight. Accordin' to Miss La Rue—she's that blond female I seen at the hotel, ain't she—Cassady was expected to reach this place where Mendez is about dawn, if he had to kill his hoss to do it. That would mean some considerable of a ride, I reckon."

"And yet," put in Westcott, with increasing interest, "would seem naturally to limit the spot to within a radius of ten miles from Badger Springs."

"Likely enough—yes; either south, southeast, or southwest; what sort o' country is it?"

"Absolutely barren; a desolate waste as far as the eye can see, except that range of mountains away to the south, fifty miles or more off. It would be a dead level, except for the sand-hills; that's all the memory I've got of it."

"Well, thar's allers some landmark to a trail, an' I used ter be a pretty fair tracker. Speed yer hoss up a bit, Jim; we've got to ride faster than this."

"How about the note she gave you?"

"We'll wait a while to read that. I don't want to strike no light just yet. Maybe it had best be kept till daybreak."

The men rode steadily, and mostly in silence, a large part of the way side by side. The animals they bestrode were fairly mated, quite capable of maintaining their gait for several hours, and needing little urging. The night air was cool, and a rather stiff breeze swept over the wide extent of desert, occasionally hurling spits of loosened sand into their faces, and causing them to ride with lowered heads. The night gloom enveloped them completely; their strained eyes were scarcely able to trace the dim outlines of the ridge road, but the horses were desert broke, and held closely to the beaten track, Before they arrived at the lone cottonwood, Westcott's pony, which carried by far the heavier load, began to show signs of fatigue. They drew up here, and the marshal dismounted, searching about blindly in the darkness.

"Too damn dark," he said, coming back, and catching up his rein. "A cat couldn't find anything there; but there's firm sand. Wait a minute; I've got a pocket compass."

He struck a match, sheltering the sputtering blaze with one hand. The light illuminated his face for an instant, and then went out, leaving the night blacker than before.

"That's south," he announced, snapping the compass-case shut, "and this blame wind is southeast; that ought to keep us fairly straight."

"The ponies will do that; they'll keep where the travelling is good. Shift this bag back of your saddle, Dan. You ride lighter, and my horse is beginning to pant already; that will ease him a few pounds."

The transfer was made, and the two men rode out into the rear desert, urging their animals forward, trusting largely to their natural instinct for guidance. They would follow the hard sand, and before long the scent of water would as certainly lead them directly toward the spring. With reins dangling and bodies crouched to escape the blast of the sharp wind, neither spoke as they plunged through the gloom which circled about them like a black wall.

Yet it was not long until dawn began to turn the desert grey, gradually revealing its forlorn desolation. Westcott lifted his head, and gazed about with wearied eyes, smarting still from the whipping of the sand-grit. On every side stretched away a scene of utter desolation, unrelieved by either shrub or tree—an apparently endless ocean of sand, in places levelled by the wind, and elsewhere piled into fantastic heaps. There were no landmarks, nothing on which the mind could concentrate—just sand, barren, shapeless, ever-changing form, stretching to the far horizons. The breeze slackened somewhat as the sun reddened the east, and the ponies threw up their heads and whinnied slightly, increasing their speed. Westcott saw the marshal arouse himself, straighten in the saddle, and stare about, his eyes still dull and heavy.

"One hell of a view, Jim," he said disgustedly, "but I reckon we can't be a great ways from that spring. We've been ridin' right smart."

"It's not far ahead; the ponies sniff water. Did you ever see anything more dismal and desolate?"

"Blamed if I see how even a Mex can run cattle through here."

"They know the trails, and the water-holes—ah! there's a bunch o' green ahead; that'll likely be Badger Springs."

Assured they were beyond pursuit, the two unsaddled, and turned the ponies out to crop the few handfuls of wire grass which the sweet water bubbling up from a slight depression had coaxed into stunted growth. There was no wood to be had, although they found evidence of several camp-fires, and consequently they were obliged to content themselves with what they could find eatable in their bag. It was hardly a satisfying meal, and their surroundings did not tend toward a joyful spirit. Except for a few sentences neither spoke, until Brennan, having partially satisfied his appetite, produced the note given him by Miss La Rue, and deliberately slashed open the sealed envelope.

"In the name of the law," he said grimly, hauling out the enclosure.
"Now we'll see what's the row. Holy smoke! it's in Spanish! Here,
Jim, do you read that lingo?"

"I know words here and there," and Westcott bent over the paper, his brows wrinkling. "Let's see, it's not quite clear, but the sense is that Mendez will be paid a thousand dollars for something—I can't make out what, only it has to do with prisoners. Lacy says he'll be there to confer with him some time to-night."

"Where? At Sunken Valley?"

"The place is not mentioned."

"Lacy write it?"

"Yes; at least he signed it; there's a message there about cattle, too, but I can't quite make it out."

"Well, we don't care about that. If Lacy aims to meet Mendez to-night, he ought to be along here soon after nightfall. How'd it do to hide in these sand-hills, and wait?"

"We can do that, Dan, if we don't hit any trail," said Westcott, leaning over, his hand on the other's knee, "but if we can get there earlier, I'd rather not waste time. There's no knowing what a devil like Mendez may do. Let's take a scout around anyhow."

They started, the one going east, the other west, and made a semicircle until they met, a hundred yards or so, south of the spring, having found nothing. Again they circled out, ploughing their way through the sand, and all at once Brennan lifted his hand into the air and called. Westcott hurried over to where he stood motionless, staring down at the track of a wagon-wheel. It had slid along a slight declivity, and left a mark so deep as not yet to be obliterated. They traced it for thirty feet before it entirely disappeared.

"Still goin' south," affirmed the marshal, gazing in that direction. "Don't look like there's nothin' out there, but we might try—what do you say?"

"I vote we keep moving; that wagon is bound to leave a trail here and there, and so long as we get the general direction, we can't go far wrong."

"I reckon you're right. Come on then; let's saddle up."

It was a blind trail, and progress was slow. The men separated, riding back and forth, leaning forward in the saddles, scanning the sand for the slightest sign. Again and again they were encouraged by some discovery which proved they were on the right track—the clear print of a horse's hoof; a bit of greasy paper which might have been tied round a lunch, and thrown away; impresses in the sand which bore resemblance to a man's footprints; a tin can, newly opened, and an emptied tobacco-pouch. Twice they encountered an undoubted wheel mark, and once traces of the whole four wheels were plainly visible. These could be followed easily for nearly a quarter of a mile, but then as quickly vanished as the wagon came again to an outcropping of rock. Yet this was assured—the outfit had headed steadily southward.

This was desperately slow work, and beyond that ridge of rock they discovered no other evidence. An hour passed, and not the slightest sign gave encouragement. Could the wagon have turned in some other direction? In the shadow of a sand-dune they halted finally to discuss the situation. Should they go on? Or explore further to the east and west? Might it not even be better to retrace their way to the springs, and wait the coming of Lacy? All in front of them the vast sand plain stretched out, almost as level as a floor. So far as the eye would carry there was no visible sign of any depression or change in conformity. Certainly there was no valley in that direction. Beyond this dune, in whose shelter they stood, there was nothing on which the gaze could rest; all was utter desolation, apparently endless.

Brennan was for turning back, arguing the uselessness of going further, and the necessity of water for the ponies.

"Come on, Jim," he urged. "Be sensible; we've lost the trail, and that's no fault o' ours. An Apache Indian couldn't trace a herd o' steers through this sand. And look ahead thar! It's worse, an' more of it. I'm for stalking Lacy at the springs." He stopped suddenly, staring southward as though he had seen a vision. "Holy smoke! What's that? By God! It's a wagon, Jim; an' it come right up out of the earth. There wasn't no wagon there a second ago."