And Black Bart stayed with his work. Now he struck out a wide circle, running always with his nose close to the ground. Again he doubled back sharply to the barn-site, and began again in a new direction. He ran swiftly, sometimes putting his injured leg to the ground with hardly a limp, and again drawing it up and running on three feet. In a moment he passed out of sight behind a slight rise of ground to the left of the ash-heaps, and at some little distance. He did not reappear. Instead, a long, shrill wail came wavering towards the doctor and Dan Barry. It raised the hair on the head of the doctor and sent a chill through his veins; but it sent Whistling Dan racing towards the place behind which Black Bart had disappeared. The doctor hurried after as fast as he might and came upon the wolf-dog making small, swift circles, his nose to the ground, and then crossing to and fro out of the circles. And the face of the master was black while he watched. He ran again to Bart and began talking swiftly. "D'you see?" he asked, pointing. "From behind this here hill you could get a pretty good sight of the barn--and you wouldn't be seen, hardly, from the barn. Someone must have waited here. Look about, Bart, you'll be findin' a pile of signs, around here. It means that them that done the shootin' and the firin' of the barn stood right here behind this hill-top and watched the barn burn--and was hopin' that Satan and you wouldn't ever come out alive. That's the story." He dropped to his knees and caught Bart as the big dog ran by. "Find'em, Bart!" he whispered. "Find'em!" And he struck sharply on the scar where the bullet had ploughed its way into Bart's flesh. The answer of Bart was a yelp too sharp and too highly pitched to have come from the throat of any mere dog. Once more he darted out and ran here and there, and Doctor Byrne heard the beast moaning as it ran. Then Bart ceased circling and cut down the slope away from the hill at a sharp trot. A cry of inarticulate joy burst from Dan, and then: "You've found it! You have it!" and the master ran swiftly after the dog. He followed the latter only for a short distance down the slope and then stood still and whistled. He had to repeat the call before the dog turned and ran back to his master, where he whined eagerly about the man's feet. There was something uncanny and horrible about it; it was as if the dumb beast was asking for a life, and the life of a man. The doctor turned back and walked thoughtfully to the house. At the door he was met by Kate and a burst of eager questions, and he told, simply, all that he had seen. "You'll get the details from Mr. Barry," he concluded. "I know the details," answered the girl. "He's found the trail and he knows where it points, now. And he'll want to be following it before many hours have passed. Doctor Byrne, I need you now--terribly. You must convince Dan that if he leaves us it will be a positive danger to Dad. Can you do that?"