Percy Rapson discovered the lumbering wagon by the cloud of dust which rose above the pine-trees half-way along the valley. He reined in his broncho and waited on the ridge of the hill until his two companions in the uniform of the North-West Mounted Police should rejoin him.

The loud crack of a teamster's whip had told him that there were strangers on the trail beyond this intervening hill.

"There goes the outfit that made the track we've been following up all the afternoon," he announced, pointing in the direction of the cloud of white dust. "Whose is it, I wonder?" he questioned, speaking more particularly to the one who wore a triple chevron on the arm of his faded red tunic. "Looks rather unusual, doesn't it, Silk?"

Sergeant Silk drew down the wide brim of his hat, to shield his eyes from the glare of the setting sun, and contemplated the distant vehicle with its white canvas roof and its plodding team of mules.

"I expect it's a party of prospectors going west to the diggings," remarked Trooper Medlicott, riding up to his side.

Sergeant Silk shook his head.

"It isn't that," he decided. "It's not the best time of the year to start for the diggings, winter coming on. And besides, a woman—a girl—would hardly be going alone on a journey like that."

Young Rapson looked at him sharply.

"A girl?" he repeated wonderingly. "But you can't possibly see her, all this way off! How do you know?"

"Come to that, I don't know—with any certainty," Silk returned. "And, of course, as you say, I couldn't see her all this distance off, even if she were not hidden under the awning. Who could?"

"But you never say things like that at random," pursued Rapson. "You've always got a good reason for everything you do and say."

"Exactly," Silk nodded. "But it's only my surmise that there's a girl in that wagon. I don't insist that she's alone. There's the teamster and the off man taking charge of the outfit, even if their passenger had no other companion than her dog. She's young," he went on, as if speaking to himself, "and I guess she has fair hair. A bit of an artist, I believe. Paints landscapes. I'm inclined to promise that if you were to overhaul her fixings, Percy, you'd find she has a sketch of Minnewanka Peak in her portfolio."

"My hat!" exclaimed Percy. "Say, you're clever to have figured out all that!"

The sergeant shrugged his shoulders.

"Clever? Not at all," he protested. "I've only found out what you or Medlicott or any one else might have discovered equally well. It's quite simple. I merely happened to notice a few little things back along the trail where we halted to have our grub. You noticed yourself that somebody'd been camping there in front of us, didn't you?"

"Yes," Rapson signified. "I couldn't help seeing the ashes of their bivouac fire; and, of course, I've noticed the track of their wagon wheels all along the trail, as well as the footmarks of a rather big dog. But I fail to understand how you can make out all that information about the girl having fair hair and bein' an artist."

Sergeant Silk smiled as he turned to lead the way down the slope of the hill trail into the valley.

"That's only because you don't smoke a pipe that needs occasional cleaning out," he responded. "Mine needed cleaning, see? and while you and Bob Medlicott were down at the creek, watering the horses, I looked about for a stalk of sage-grass or something that would go into the stem. I found just the very thing I wanted—a hair-pin. You'll allow that a hair-pin is peculiarly a feminine piece of furniture. It's reasonable to infer that it wasn't a man who lost it; and since the one I picked up was made of gilt wire, I guess it wasn't the property of a woman with black hair. What? Don't you agree with me?"

Percy Rapson was laughing.

"It's too ridiculously obvious to be disputed," he acknowledged. "But," he added inquiringly, "how about the supposed sketch of Minnewanka Peak? That's a corker!"

Silk pushed back his hat.

"For one thing," he explained, "she sharpened a black-lead pencil, leaving the chips lying around, close beside the marks in the soil where her easel and camp-stool had stood, the dog sitting near. She had thrown away a bit of rag on which she had cleaned her paint-brushes. She'd used more azure blue than any other colour, and, say, I don't know anything quite so blue as Minnewanka Peak, of which she had an excellent view from where she had propped her easel."

"Rather a jolly idea, that—touring about Canada takin' sketches of the scenery," observed Percy Rapson. "I've often wished to be an artist. Do you suppose that she would let us have a look at her sketches, Silk?"

"There'd be no great harm in your asking her," the sergeant answered. "But we shall hardly have time to loiter around. You see, Medlicott and I are on special duty. We're not here to occupy our time with strangers; unless, of course, we can be of some help to them. We've got to follow up the trail of Nick-By-Night and his gang, and hale them off to prison—if we're lucky enough to lay hands on them."

Percy Rapson glanced forward to the cloud of dust.

"Risky for an unprotected girl to be travellin' about when there are such characters as Nick-By-Night on the trail," he said. "I wonder nobody warned her against the possibility of bein' held-up by bandits."

"There is certainly that danger," Silk said with a tone of anxiety in his voice. "It was only half-a-dozen miles beyond where we are now that the bandits, as you call them, escaped from the patrol a week ago. Nick's secret hiding-place is somewhere over the hills there, on Ghost Pine Creek."

"Then that is where you are bound for?" Percy Rapson inquired. He had met the two Riders of the Plains unexpectedly, earlier in the day, and had continued to ride in their company, intending to break off from them on reaching the cross trail leading to his home at Rattlesnake Ranch.

"Exactly," Silk answered.

"Are you going to allow me to stand in with you?" the boy asked.

The sergeant shook his head.

"It would hardly be wise," he responded. "You might get hurt. There's sure to be some shooting, and I don't figure that I shall need you to identify him. I shall know him when I see him."

"You ought to," rejoined Percy. "You've seen him before."

"Eh?" Sergeant Silk looked aside at him in curious surprise. "I've seen him before, you say? When? Where?"

"Six months ago," Rapson answered, "at Calgary Races. I was there at the time, only you didn't know me very well then. It was in the Golden Bar saloon. I dare say you would have arrested him then, only there was a nasty scuffle; you were wounded, and he gave you the slip."

Silk checked his mare's pace and stared at his young friend in a puzzled manner.

"Do you mean that swell mobsman with the diamond ring?" he questioned. "The chap who was playing three-card monte? Was that Nick-By-Night?"

"That's the chap, sure," Rapson informed him. "He'd done me out of two pounds by that sharper's trick of his, and I'd followed him and his gang of confederates into the saloon to try to get my money back. You remember what happened?"

"I am not likely to forget," answered the sergeant, "since apart from the wound, which was not worth mention, it was the one occasion in my experience on which I have known the excitement of pitting my common-sense against the skill of a professional swindler."

Percy recalled the exciting incident to his own memory now as he followed the red-coated officer down the trail. He pictured to himself the noisy saloon, thronged with racing men, cowboys, ranchers, idlers from the town and the outlying homesteads, with a sprinkling of Indians and half-breeds.

He saw a tall, lithe, blue-eyed man, dressed as a rancher, in corduroys, blue shirt, and wide felt hat, slowly threading his way, as though without definite aim, among the little tables at which men sat drinking, smoking, gambling. Percy did not recognise him at first in his disguise, never before having seen him out of his smart uniform of the Mounted Police; but presently he overheard a half-breed muttering—

"Parbleu! yes; it ees Sergean' Seelk! He shape for mek de arrest of Monsieur Cutlaire. What?"

Rapson watched the sergeant saunter up to the table at which the card-sharper now sat with a couple of companions as flashily dressed as himself.

"Say, stranger, what kind of a lay-out d'you call this?" Silk inquired in a slow, drawling voice, without removing the cigarette from his lips.

The sleek, clean-shaven, flashily dressed man with the diamond ring looked up at him without suspicion, evidently supposing that he was what he appeared to be—a careless, good-natured, easy-going rancher out for a holiday; a likely victim to be gulled and fleeced.

"What sort of eyesight have you got, cully?" the gambler asked, holding up three cards with their faces outwards, so that the newcomer might see them.

"Oh, I dunno," said Silk, trying to look stupid. "Pretty middlin', I reckon. Why?"

"Say, now," went on the three-card man, "d'you reckon you could locate the king when I throw them out, this way?"

"Why, cert'nly," declared Silk, pointing at one of the cards. "It's that one."

"My!" ejaculated the dealer in pretended surprise. "So it is! You're not such a cariboo as you look. But I bet you five dollars you can't do it a second time."

"Right you are," Silk agreed, producing a five-dollar bill. "Show your money."

For a second time he was allowed to pick out the king and to take possession of the stakes. The table was now surrounded by a pressing crowd of onlookers, including Percy Rapson, who tried to attract the sergeant's attention and to caution him against the certainty of being swindled; but Silk held his face down, shadowed by his wide felt hat, all his attention upon the game.

"You've got the eyes of a lynx," commented the dealer encouragingly. "You'll sure make your pile at this rate. Try once more!"

The cards were thrown again, and again the supposed rancher won. He made a clever show of becoming eager, though he knew that he was only being decoyed to a final plunge. When he had won twenty dollars and the watching crowd had drawn closer, he laughed and glanced across at the sharper.

"Say, do you put any limit on this here game?" he asked.

"How far will you go?" questioned the dealer. "You're twenty dollars to the good already. You're shaping to break me."

Sergeant Silk hesitated and looked swiftly back over his shoulder. He wanted to delay operations until one or more of his chums of the Mounted Police should come in to his support, as had been planned in case of trouble.

"How much do you bet?" invited the sharper.

Silk leant forward, fumbling at his belt pocket.

"Fifty dollars," he readily answered.

The man with the diamond ring made a pretence of hesitation. Silk deliberately counted out ten five-dollar bills and held them between his fingers on the table.

"All right," the gambler assented, taking up what appeared to be the same three cards. "I don't mind running the risk, just for once on the off-chance of my luck taking a turn."

And he began to make passes with the three pieces of pasteboard.

"Wait a bit, though," objected Silk very calmly. "I don't see your own stake. Here is my money. Where's yours?"

"Oh, that's all serene," said the other. "My credit's good for anything in this emporium."

"May be so," demurred Silk. "All the same," he insisted firmly, "I expect to see your money alongside of mine."

There was some quibbling, but after consulting with one of his confederates the gambler yielded and reluctantly counted the money in gold from a bulky canvas bag that he drew from his breast pocket. Probably Silk was the only stranger present who was aware that the coins were counterfeit.

"That ought to satisfy you," sneered the trickster, as he dealt out the three cards.

Very coolly and without an instant's hesitation Sergeant Silk bent over and placed his hand upon the card nearest to him, drawing it an inch or two towards him, but not turning it up.

"This is the king," he declared positively, for the first time looking the gamester straight in the eye.

"Ah, so that's your fancy, is it?" The professional swindler leant back with a satisfied smile. "Well, suppose you just turn it over and let every one see."

Silk's steel-blue eyes flashed for an instant. He knew that with his next move there was going to be trouble.

"No," he cried. "You will turn over the other two."

With an oath the swindler refused, betraying by his agitation that for once he had met his match.

"That's not the way this game is played," he objected in confusion. "Show us your king."

"It's the way that I intend to see it played," declared Silk very calmly but firmly. And with his forefinger he adroitly flicked the two cards over, face upward. "You see," he cried, "neither of yours is a king. Therefore mine is bound to be."

Utterly confounded, and dreading the consequences if the third card should now be revealed, the swindler tried to shuffle out of his awkward position by giving in.

"In that case, you win," he said.

Sergeant Silk quietly pocketed the hundred dollars with one hand, while with the other he still retained the third card.

The gambler snatched at it.

"Give me that card!" he demanded, dreading that any one should see it.

Silk laughed and stood up.

"Not before the company have seen it," he retorted, and turning the card over he cried: "See, boys, it's the three of diamonds! The king is up his sleeve!"

His voice, the accusing flash of his eyes, his whole attitude, revealed him in his true identity to the crowd, who now recognised him through his disguise as a well-known officer of the Mounted Police. There was a cry—

"It's Silk—Sergeant Silk!"

In the wild confusion that followed his exposure of the cheat, Percy Rapson did not see exactly what happened. All that he knew was that the unmasked card-sharper and his confederates were fighting their way out of the saloon, that one or two pistol shots were fired, and that Sergeant Silk had been flung to the floor with blood upon his face.

"So that was Nick-By-Night, was it?" Silk now asked of Rapson as they rode into the valley. "How do you know?"

"I found out only this morning," Percy explained. "I was at Hilton's Jump and heard two fellows talking about him in Canadian French. They called him Nick Cutler, and Cutler was the name by which Pierre Roche referred to the card-sharper in the Golden Bar. I expect he has heaps of aliases and disguises. Anyhow, you'll know him when you see him, won't you?"

"Why, cert'nly," nodded Silk, "thanks to you. You see, I never forget a face."

"Say, Sergeant," interposed Constable Medlicott, "that outfit in front of us has pulled up. I guess they're intending to make camp for the night."

"Do you suppose they've spotted us?" questioned Percy Rapson.

"It's likely," said Silk. "What if they have?"

"Well," returned Percy, looking serious, "I was thinkin' it might be a trap. It's quite possible that the man you're trackin'—Nick-By-Night—is in that wagon with some of his gang, lying in wait for you, and that he planted that hair-pin and the other signs to decoy you."

Silk smiled.

"It's 'cute of you to hit upon such a notion," he said, "but, you see, it was by the merest chance that we halted where we did; and besides, the innocent hair-pin was dropped there quite early in the morning, before I myself knew we were coming on this trail. Just in case there is any trickery, however, I will ride on in advance, and if I find that the wagon is occupied by a gang of armed bandits, I'll sound my whistle. You two will wait right here."