sky, swung toward the horizon.

Threading his way carefully through one of the passes of the Cajons was a cowboy on a sorrel horse. Dust lay thick on both horse and rider, for they had been long on the trail that day and there had been no rain in the Cajon country for weeks.

Breasting the last steep grade leading to the summit of the pass, a new country was unfolded. The sorrell paused as its rider dismounted more than a little stiff from the hours in the saddle and the intense heat of the day.

The cowboy patted the sorrel affectionately.

“It’s been a long grind, Lightning, old girl. We’ll rest here a few minutes and then see if we can find a good place to camp tonight.”

The narrow trail had broadened at the summit and there was a swale with a little grass that had escaped the burning rays of the midsummer heat.

The sorrel began to graze while the cowboy sat down in the shadows of a boulder.

All day long horse and rider had been toiling up the slope from the east, following the little-used trail. Shading his eyes, the cowboy tried to follow the trail. It turned west and north, into a country that was well timbered and appeared to be rich in grazing land--a country new to both horse and rider.

For the twentieth time in the last three days the cowboy slipped his hand into an inner pocket and drew forth an envelope. He unfolded the letter it contained and scanned it with puzzled eyes. It was addressed to Slim Evans, Flying Arrow Ranch, Sunfield, Wyo.

“Dear Slim,” the letter began, “I am in need of your help. Things are going badly in the Creeping Shadows country over beyond the Cajons and I am counting on you to straighten out the trouble. The greatest secrecy is necessary so let no one except your father know of this message. Meet me on the 22nd at the foot of the Sky High trail on the other side of the Cajons. Will explain everything then.”

The message was signed by Bill Needham, secretary of the Mountain States Cattlemen’s Association.

Slim Evans folded the letter and slipped it back into the envelope, which was now badly creased.

It had been a summons he could not disregard and the mysterious tone of the letter had aroused his curiosity. Once or twice in the last two years he had been able to help Bill Needham and the Mountain States Association in running down rustlers. Bill was an old friend of the Evans family and Slim had hastened to roll his duffel and start for the Sky High trail over the Cajons.

It was the best part of another day’s ride to the foot of the trail, but he could slacken the fast pace he and Lightning had maintained for he was well within the time limit.

Fine lines puckered Slim’s brow as he stared down from the summit of the trail toward the Creeping Shadows country. Although less than a hundred and fifty miles from the Flying Arrow, where he had been reared, it was new country to him, right against the southern boundary of Montana with the Bad Lands touching it on the east.

Slim wondered if Needham was calling him in on a case of cattle rustling. But that seemed hardly possible, for the association had a small staff of men who devoted all of their time and energy to running down cattle thieves. Slim’s only work along that line had been several small investigations near the home ranch where he had been able to save the association the expense of sending out one of its staff detectives.

Bill Needham was the only man with the answer and Slim reluctantly left the cool shadow of the rock. Lightning responded to his whistle and the cowboy swung into the saddle.

“Half an hour more, Lightning, and we’ll look for a camp,” said Slim, running his fingers through the mane of his mount.

Lightning, a beautiful horse, was tall, well built, with legs strong enough to stand a terrific speed even in the roughness of the cow country.

A white star stood out on her forehead and each foot had a collar of white just above the fetlock. It was evident that horse and rider understood each other for, from time to time, Slim spoke to Lightning and the mare seemed to nod in reply.

The Sky High trail had been in little use for half a dozen years, the new trail through the Cajons went nine miles south along an easier pass. Years before the Sky High trail had been one of the main routes through the mountains, cowboys and herds from the Creeping Shadows country thundering along it. Now the old road was covered with weeds and only a semblance of a trail remained.

For half an hour Slim and Lightning swung down from the summit at a steady pace. The trail rounded a rocky promontory and a small patch of timber ahead hinted of a suitable camping place.

A mountain stream, grown thin from lack of rain, stumbled along over its rocky bed. There was enough grass and plenty of shelter. Slim dismounted, loosened the cinches, and pulled the heavy saddle and blanket from Lightning’s back. He slipped the bit out of the sorrel’s mouth, tossed the reins over the magnificent head, and Lightning was free to graze for whatever morsels of grass could be found in the little valley.

Slim unfastened the slender duffel roll he carried behind the saddle and brought out the mess kit. He was traveling light.

Before preparing his own evening meal, he slipped off the well-worn leather chaps which protected his legs and went down to the little stream. The water was cool and sweet and he drank deeply from the hurrying creek. Then he washed thoroughly, finally dousing his head in the water.

When he cleared the water from his eyes he saw Lightning standing a little below him and looking at him reproachfully.

Slim laughed. “Better try a little water to wash off the dirt,” he chuckled.

But Lightning snorted disdainfully, drank deeply, and returned to graze again.

The cool water refreshed Slim greatly and he set about the task of preparing his evening meal. There was still a half hour of daylight, but he had been in the saddle at sun-up and, toughened though he was to the life of the range, the heat had tired him. He was ready to roll into his blanket as soon as he finished his meal.

There was plenty of dry wood in the patch of timber and Slim soon had a small, smokeless fire going. Plenty of bacon, bread that now was none too fresh, and a small pot of coffee completed food for supper.

Slim had just finished turning the bacon to a crisp, delicious brown, and the coffee was simmering in the coals when a rifle shot echoed from below.

The cowboy paused, bacon halfway between his tin plate and his mouth. There was another shot, followed by a fusillade. Slim heard the sudden scream of pain of a mortally wounded horse and he finished the bacon in one gulp.

“Lightning!” he called.

The sorrel, now a hundred yards away, heard the cry and came at a full gallop.

Slim leaped across the campfire and dove into the small pile of duffel beside his saddle. From a saddlebag he drew a cartridge belt and holster. This he buckled swiftly around his waist, pausing only long enough to make sure that the heavy .38 in the holster was free.

From a boot fastened to the saddle he drew a Winchester 30-30. A glance told him that the magazine was full and he swung an extra belt of ammunition over his shoulder.

The firing down below was coming steadily. There was no time to saddle and Slim leaped upon Lightning and went dashing down the Sky High trail.

At a mad gallop, Slim and Lightning raced down the valley. Like the true cow horse, Lightning sensed obstacles almost before they were in sight and on more than one occasion stretched her long legs to leap across badly washed places in the trail. At the pace they were going, a tumble would have been fatal for both.

The valley broadened and the timber thinned out. Slim reined Lightning in sharply. Ahead of them was a great wash