There was a thin, crisp, continuous patter from somewhere in the heart of that crawling bank. The cloud was within fifty yards of where we lay, and we glared at it, all three, uncertain what horror was about to break from the heart of it. I was at Holmes’s elbow, and I glanced for an instant at his face. It was pale and exultant, his eyes shining brightly in the moonlight. But suddenly they started forward in a rigid, fixed stare, and his lips parted in amazement. At the same instant Lestrade gave a yell of terror and threw himself face downward upon the ground. I sprang to my feet, my inert hand grasping my pistol, my mind paralyzed by the dreadful shape which had sprung out upon us from the shadows of the fog. A hound it was, an enormous coal-black hound, but not such a hound as mortal eyes have ever seen. Fire burst from its open mouth, its eyes glowed with a smouldering glare, its muzzle and hackles and dewlap were outlined in flickering flame. Never in the delirious dream of a disordered brain could anything more savage, more appalling, more hellish be conceived than that dark form and savage face which broke upon us out of the wall of fog.

With long bounds the huge black creature was leaping down the track, following hard upon the footsteps of our friend. So paralyzed were we by the apparition that we allowed him to pass before we had recovered our nerve. Then Holmes and I both fired together, and the creature gave a hideous howl, which showed that one at least had hit him. He did not pause, however, but bounded onward. Far away on the path we saw Sir Henry looking back, his face white in the moonlight, his hands raised in horror, glaring helplessly at the frightful thing which was hunting him down. But that cry of pain from the hound had blown all our fears to the winds. If he was vulnerable he was mortal, and if we could wound him we could kill him. Never have I seen a man run as Holmes ran that night. I am reckoned fleet of foot, but he outpaced me as much as I outpaced the little professional. In front of us as we flew up the track we heard scream after scream from Sir Henry and the deep roar of the hound. I was in time to see the beast spring upon its victim, hurl him to the ground, and worry at his throat. But the next instant Holmes had emptied five barrels of his revolver into the creature’s flank. With a last howl of agony and a vicious snap in the air, it rolled upon its back, four feet pawing furiously, and then fell limp upon its side. I stooped, panting, and pressed my pistol to the dreadful, shimmering head, but it was useless to press the trigger. The giant hound was dead.