Like a period to his sentence, a gun barked outside, there was a howl of demoniac pain and rage, and then a scream that would tingle in the ear of Doctor Randall Byrne till his dying day. CHAPTER XXIII HOW MAC STRANN KEPT THE LAW For when the dog sprang, Mac Strann fired, and the wolf was jerked up in the midst of his leap by the tearing impact of the bullet. It was easy for Strann to dodge the beast, and the great black body hurtled past him and struck heavily on the floor of the barn. It missed Mac Strann, indeed, but it fell at the very feet of Haw-Haw Langley, and a splash of blood flirted across his face. He was too terrified to shriek, but fell back against the wall of the barn, gasping. There he saw Black Bart struggle to regain his feet, vainly, for both of the animal's forelegs seemed paralyzed. Now the yellow light of the fire rose brightly, and by it Haw-Haw marked the terrible eyes and the lolling, slavering tongue of the great beast, and the fangs like ivory daggers. It could not regain its feet, but it thrust itself forward by convulsive efforts of the hind legs towards Mac Strann. Haw-Haw Langley stared for a single instant in white faced fear, but when he realised that Black Bart was helpless as a toothless old dog, the tall cowpuncher, twisted his lean fingers with a silent joy. Once more Bart pushed himself towards Mac Strann, and then Haw-Haw Langley stepped forward, and with all the force of his long leg smashed his heavy riding boot into the face of the dog. Black Bart toppled back against the base of the manger, struggled vainly to regain his poise, and it was then that he pointed his nose up, and wailed like a lost soul, wailed with the fury of impotent hate. Mac Strann caught Haw-Haw by the arm and dragged him back towards the door. "I don't want to _kill_ the dog," he repeated. "Get out of here, Haw-Haw. Barry'll be comin' any minute." He could have used no sharper spur to urge on the laggard. Haw-Haw Langley raced out of the barn a full stride before Mac Strann. They hurried together to the little rise of ground behind which they had left their horses, and as they ran the scream which had curdled the blood of Randall Byrne rang through the night. In a thousand years he could never have guessed from what that yell issued; his nearest surmise would have been a score of men screaming in unison under the torture. But Mac Strann and Haw-Haw Langley knew the sound well enough.