father, though only a Canadian farmer,had been a man of considerable culture and learning, and had seen thathis son, who inherited his own intellectual gifts, had been well taught.Only the spirit of adventure had led him at twenty-one into the wildplaces of the world, where he saw existence from many angles, and in arough outdoor life had brought to perfection physical powers which hadbeen remarkable even in boyhood.

  He was now the last of the Renstokes. But he was still young. No onedreamed but that he would marry and that the ancient line would becontinued.

  Then the blow fell!

  Through the late summer a series of mysterious attacks had been made onlive stock throughout the western portion of Argyllshire. Sheep, andeven deer, had been attacked, evidently by some unusually powerfulanimal.

  Sheep worrying, of course, is not an uncommon vice among dogs, and whenthe outbreak first started little was thought of the matter. The localfarmers and shepherds merely began to watch their dogs more closely thanusual. But the outbreaks continued, more and more sheep were killed,and at length the losses became so heavy that drastic steps were taken.

  For thirty miles around, not a dog was permitted off the chain afterdusk. Bands of men armed with guns, with instructions to shoot any dogon sight, patrolled the country-side by day and night. It was all invain. Sheep continued to perish under the teeth of the mysteriousprowler, and even the smaller deer, in spite of their speed, began tofall victims.

  The farmers were at their wits' ends when the mystery was suddenlylifted into the region of unadulterated horror.

  Alan MacPherson, a young gamekeeper, had been one of a number of menwho, stretched out into a line a couple of miles long, had set out atnightfall to search a lonely piece of moorland in which it was thoughtthe strange animal might be hiding. The line of men had gone forward ona prearranged plan for five or six miles and then "pivoted" on the righthand man, swung round and marched homeward, concentrating finally at abig farm known as Kelsie, where the losses had been very serious.

  The men, of course, knew the country thoroughly, and similar manoeuvreshad been many times repeated without mishap. Always the last man of theline had turned up within a few minutes of the prearranged time.

  On this occasion MacPherson was on the extreme left wheel and, havingfarthest to go, should have been the last man home. No one was uneasywhen it was found he was a few minutes late; he was armed and knew thecountry like the palm of his hand.

  But when the minutes slipped by without news his companions began to beanxious. Three hours passed, and, at length, a search party was hastilyformed.

  Two hours later MacPherson's body was found lying terribly mangledbeside a big rock on the slope of a small tor. His gun, still loaded,was only three feet away. Beside the body lay a filled pipe and a boxof matches. Evidently the man had laid down his gun to light his pipeand had been suddenly attacked and killed before he could raise a handto defend himself.

  A few minutes later, Lord Renstoke, Yvette, Dick Manton, and Jules wereon the scene. Though all were familiar with the ghastly sights of war,they found themselves in the presence of a horror which overbore alltheir previous experiences.

  Renstoke, whose experience abroad had made him familiar with many wildanimals quite unknown to the others, examined the body carefully. Atlength he rose from his knees with a horrified expression in his eyes,and gave brief orders for the removal of the body to the unfortunateman's home to await the inquest.

  But it was not until they had returned to the Castle that he spoke ofwhat he had seen. And his first words gave his comrades a terribleshock.

  "No dog did that!" he said quietly, but in a tone of intense conviction.

  "Whatever do you mean, Renstoke?" asked Dick quickly. "What else couldhave done it? There are no lions or tigers about here, you know."

  "Are you sure?" replied Renstoke. "I think we shall have to seeErckmann about this." Boris Erckmann, he went on to explain, was afamous zoologist who lived in a big lonely house on the Renstoke estatesome ten miles away. He had spent many years in wandering explorationsin tropical countries and was known in the inner circles of science as aman of brilliant attainments. He did not advertise himself, however,living the life of a recluse, and to the general public his name meantnothing. Among his Highland neighbours, a dour people who concernedthemselves very little with the affairs of other folk, little notice wastaken of him. He lived at Lockie, a big house surmounted by a high walland perched on a gaunt hill-side overlooking a lonely glen. Among hisneighbours, who guessed nothing of his wonderful abilities, Erckmannpassed for a harmless scientist and was affable and good-natured tothose he chanced to meet during his incessant pilgrimages over the widemoorland which stretched for many miles around Lockie.

  "Erckmann is said to have a lot of wild animals at Lockie," Renstokewent on to explain, "and it is possible that one of them may have brokenloose. I am perfectly certain MacPherson was not killed by a dog."

  "But what makes you so certain?" Dick questioned. "So far as I couldsee any big dog could have done it."

  "Did you ever see a dog with hands, Dick?" asked Renstoke quietly.

  His hearers started simultaneously with a gasp of horror.

  "Whatever do you mean?" they asked.

  "Just this," Lord Renstoke replied. "He was not killed by a dog at all.As you saw, the front of his throat was badly torn. But on the back ofhis neck were two distinct bruises, one on each side and nearly meeting,which suggested the mark of two thumbs, as if he had been seized frombehind by two hands which clasped his neck. Now, no dog could have donethat. Moreover no dog could have killed him so quickly that he neverhad a chance either to fight for his life or to call for help.Remember, he was an extremely powerful man and his nearest neighbour inthe line was scarcely more than a hundred yards away. He was killed sosuddenly and so swiftly that he had no time even to shout. I have seenmany men who had been killed by wolves, bears, and cougars, but neverone who had not made a fight for his life."

  "But what could it have been?" asked Yvette in a horrified whisper.

  "There is only one animal in the world that could have done it," repliedRenstoke, "and that is a gorilla. You know the strength of the gorillacompared with that of a man is enormous. It has enormously powerfulhands and teeth. A man seized unawares, as MacPherson must have been,would be dead in a few seconds; he wouldn't have the smallest chanceeither to defend himself or to shout. And I happen to know, though itis not generally known, that Erckmann actually has a gorilla at Lockie.I am going over to see him after the inquest and I mean to see thegorilla as well. Erckmann is a tenant of mine, though, as it happens, Ihave never seen him.

  "But there is one thing that puzzles me," Renstoke went on after apause. "The sheep-killing has been going on for several months, and Idon't see where such an animal as a gorilla, assuming that it has beenat large for so long, can have been hidden without being seen. But, ofcourse, the country is very wild and there are some big woods that mayhave screened it during the daytime."

  "What are you going to say at the inquest?" Dick asked abruptly.

  "Nothing at all until I know a lot more," answered Renstokedeliberately. "Remember, we don't know anything positively yet. I amonly giving you my personal opinion."

  All agreed that Renstoke's plan was best. But they had yet to learn howfar the appalling reality outstripped the horror of their suppositions.

  The inquest, held the following afternoon, was almost formal. There wasno real evidence, of course, as to how the unfortunate man was killed,and what amounted to an open verdict was found. Neither the doctor whoexamined the body, nor the detectives from Glasgow who made everypossible inquiry, struck the chain of reasoning which had led Renstoketo his strange theory, and it was generally assumed that MacPherson hadbeen killed by some ferocious dog which had been lurking unseen formonths in the wild country around Renstoke.

  Next morning all four started for Lockie. Erckmann's house, though onlyten miles away in a direct li
ne, was at least thirty by road, and as theday was fine they decided to motor for about five miles, leave the car,and walk across country for the remainder of the distance. It was thisdecision which led them to the first strange clue in the solution of theterrible mystery.

  At the point where they left the car, the road, which had been leadingwestward, made an abrupt turn at the summit of a desolate hill, andstretched away southward as far as they could see. Their destinationwas further west, and as Dick ran the car on to the grass at the side ofthe road, they prepared for their tramp.

  They had walked some four miles over rough heather-clad country whenRenstoke pointed to a big building a mile away and facing the top of thesteep rise they had just breasted.

  "That is Lockie?" he said.

  For the most part, the country was dry. Below them, however, was