He touched his mare's flank with his heel and went off at an easy gallop down the trail. As he drew near to the wagon he saw that the two men in charge of it had unharnessed the mules and were taking them to a neighbouring stream. A large deerhound appeared from behind the vehicle, followed by a girl. The hound barked at the approaching horseman.

"Quiet, Don! Quiet!" the girl called.

She stood waiting. Silk observed that she was dressed in dark serge and wore a green felt sun hat, which did not wholly conceal her very fair hair. He also noticed that she carried an artist's canvas and a portable easel.

"How do, officer?" the girl said in response to his salutation, as he drew to a halt in front of her. "The sight of your uniform is like a rainbow. It signifies hope."

"Hope?" he smiled. "Hope of what?"

"Hope that you are here to protect a lone and defenceless wayfarer from danger," she answered him. "My teamster alarms me with the news that there is a notorious highwayman prowling around in these parts. Naturally the presence of a member of the Mounted Police is reassuring." She glanced at the stripes on his arm. "Won't you dismount, Sergeant?" she asked.

Sergeant Silk slipped from his saddle.

"I'm glad to know that you have been warned," he said. "I can't deny that the warning is reasonable. As a matter of fact, we are at present hunting for that same highwayman."

"I hope you will catch him," the girl urged. "One hardly expects to be troubled by such characters in peaceful, law-abiding Alberta. I hope sincerely that he will be arrested. Do you think he will be, Sergeant? Shall I be safe, camping here?"

"You need not be afraid," Silk assured her. "Whatever else happens, Nick-By-Night shall not be allowed to interrupt your sketching tour."

The girl looked at him in amused wonder.

"My sketching tour?" she repeated. "You have not taken long to discover that I am an artist."

"The fact is obvious," he rejoined quickly, indicating the canvas that she held in her left hand. Its back was towards him, and he could not see what she had painted; but he added at a venture: "You made a picture of Minnewanka Mountain this morning."

"How do you know?" she asked in surprise. "Were you there? Did you see me at work?" She turned the canvas and held it for his inspection. "It is only a rough sketch," she explained. "I haven't come out West on a sketching tour. It is only my amusement. I am on my way to pay a surprise visit to my brother on his ranch at Mosquito Crossing. I am going to live with him, I hope, and help him with housekeeping. Perhaps you know him?"

Sergeant Silk had glanced aside at a packing-case that lay on the grass near one of the wheels of the wagon. She saw that he was reading what was written on the address label: "Miss K. Grey, Mosquito Crossing, Red Deer River, Alberta."

An expression of perplexity came upon his face.

"I did not know that any one of the name of Grey had a ranch near Mosquito Crossing," he said. "There was Andrew Grey, who ran a fruit farm near Medicine Hat; but he was too old to be a brother of yours, and besides——"

He broke off.

"My brother's name is Jim," Miss Grey explained.

"When did you last hear from him?" Silk inquired.

"Oh, months and months ago—six months, at least. It is because he hasn't written to me that I have come out to take him by surprise."

"I see," Silk nodded. "But many changes may happen in six months. I guess you had better have announced your intention. He might then have met you and saved you some trouble. Surprise visits aren't any more successful in Alberta than anywhere else. They're a mistake."

The fair-haired girl stared at him in alarm.

"Do you mean that something has happened to Jim?" she cried. "Do you mean that I shall not find him—that he has gone away—or that he is dead?"

Sergeant Silk shook his head.

"I did not say so," he responded. "I do not happen to know him, that is all that I can tell you. But, you see, there are many people in the Province of Alberta whom I do not know. Your brother is just one of them. Nevertheless, I hope I may find him for you."

"You are very kind to trouble about me," the girl told him. "I've no doubt you will find Jim, if any one can. For the present, however, I am more concerned about my personal safety from those highwaymen. You see, Sergeant, I haven't even a pistol to defend myself with."

Sergeant Silk took out a cigarette as he said—

"The situation would only be awkward if Nick-By-Night chanced to come along this trail and discover your outfit. It certainly wouldn't be nice if he were to take a fancy to your mules and leave you stranded in a lonesome place like this. But, I repeat, you need not be afraid."

He lighted his cigarette, raised his hand to a half-salute, and strode up to his broncho, while Miss Grey climbed the steps at the rear of the wagon with her easel and picture.

Silk looked down upon the dusty trail where the marks of his mare's hoofs showed amid the smaller footprints of the four mules.

"Guess we'd be wise not to disturb that track, Beauty," he decided, speaking to the mare as if she were a human.

Without giving any explanation to the girl, without even telling her that he was leaving her, he leapt into his saddle and rode down to the stream where the two wagon men were watering the mules. He spoke to the older of them, bidding him keep a big fire burning and to see that the mules were well secured. Then he entered the shallow stream and followed its current to a point near to where he had left his two companions, when he whistled to them and signed to them to come down to him.

"It's all right, Percy, my boy," he announced as they joined him. "I have interviewed the owner of the innocent hair-pin and seen her picture of Minnewanka Peak. It's great! I find she is some scared about Nick-By-Night. She's got some fixings that would be worth his stealing, and—well, if you two chaps see no objection, I figure we may as well hang around hereabout until morning."

"Joining Miss Hair-pin's encampment?" questioned Percy.

"Not exactly," Silk answered, "but keeping an eye on it from ambush."

"Why did you come back along the bed of the stream?" Percy wanted to know. "Why did you bring us off the trail?"

"Just a whim of mine," smiled the sergeant. "I didn't want to make a return track. I wanted you two to leave the hoof-marks of two horses leading off the trail. There'll be a full moon to-night, and if any one—any bandit or highwayman—should follow on our traces, he'll think just what I mean him to think, that two of us have gone off on a side track, leaving the wagon unprotected."

"Say, you wouldn't take such elaborate precautions if you didn't suspect that something was goin' to happen," declared Percy. "But, of course, you couldn't well leave a mere girl in such a situation."

"That is what I thought," said Silk. "We will lie in our blankets within close call."

He led his companions back on the far side of the stream, and they took up a position, well concealed, between the water and Miss Grey's camp fire, hobbling their horses beside them. They had food in their haversacks, and when they had taken supper the sergeant claimed first turn for a sleep.

At midnight he was on watch alone, sitting with his back against a tree-trunk and his carbine across his knees, while Medlicott and Rapson rested. The moon was shining brightly, making everything almost as clear as in daylight. All was quiet excepting for the occasional movement of one of the horses, the croaking of bull frogs, and the harsh chirping of night insects. Suddenly a new sound fell upon his ear. He put forth his hand and touched Trooper Medlicott.

"You awake, Bob?"

"I am listening," whispered Medlicott. "There's two of 'em. They're coming this way on the trail of the wagon. They've passed the place where we forked off."

"Maybe they're a couple of our own boys," said Silk. "But whoever they are, they'll sure pull up near the camp fire to nose around. Follow me up. Bring Rapson; but keep him well in the rear. There's the deerhound barking!"

He tightened the cinches of his saddle, and, mounting, rode up very cautiously towards the fire. His overcoat covered his red tunic, and the two teamsters, who were awake and on their feet, neither saw nor heard him as he moved stealthily among the black shadows of the trees bordering the trail between the wagon and the approaching horsemen.

Nearer and nearer they came. For a long time Silk listened to the sound of their horses' hoofs, watching for them to cross into a wide stretch of moonlit grass. Trooper Medlicott was now close behind him. Percy Rapson was far back.

"Here they come!" whispered Sergeant Silk. "Be ready to give chase. They're both masked."

He rode boldly out to meet them, halting in the middle of the trail and raising his carbine.

"Who goes?" he cried. "Pull up, or I fire!"

The two masked riders dragged their horses round and made off by the way they had come. They were in the full light. Silk fired two shots in quick succession. One of the horses staggered, went down on its knees, and rolled over. The other dashed on. Silk fired again, then put spurs to his broncho and rode off in pursuit, with Medlicott following.

"Look to the one that's fallen!" he cried.

Percy Rapson rode out also, to help Medlicott. The man who had been thrown had broken a leg and could not move. Medlicott quickly disarmed him and left him in charge of Percy, who stood over him until the two policemen returned with their captive riding between them.

"This chap's plug is done for, Sergeant," Percy reported.

"I'm sorry for that," Silk regretted. "Help him to mount yours and lead him to the wagon. I must see to that broken leg of his. We shall stop here until daybreak."

Their two prisoners were led into the circle of light made by the camp fire. The one with the broken limb was put to lie on a blanket until he could be properly attended to. The other was secured against escape by means of a trail rope, which was bound about his wrists and ankles. Percy Rapson watched this operation with interest, admiring the skill with which Sergeant Silk tied the knots and combined absolute security with freedom to move. It was not until the last knot was tied that the man's mask was removed.

"That's him, sure enough!" declared Percy when the outlaw's face was revealed. "That's the chap who tried to swindle you, Sergeant—Nick Cutler—Nick-By-Night!"

The prisoner was writhing curiously, bending forward, and staring towards the wagon. Sergeant Silk turned to see what he was looking at so intently, and beheld Miss Grey standing in the firelight, wrapped about in a rich fur coat.

"I am sorry to have disturbed you," Silk said to her apologetically. "But, you see, we have caught your highwayman. Say, you had better get back into the wagon and finish your sleep."

She did not seem to hear him. Her eyes were fixed in blank amazement upon his prisoner's face. Silk moved aside and she made a step forward, pointing a trembling hand at the man writhing in his ropes.

"Jim!" she cried. "Jim!"

The captured outlaw drew back as if from a blow.

"Kitty!" he faltered. "Kitty! You—here?"

The girl waved her hand to dismiss him from her sight, then turned to the tall soldier policeman who stood near her, betraying no surprise at the strange recognition.

"It's all right, Sergeant," she murmured brokenly. "You have found my brother for me, as you said you would."