The two boys arrived back at the camp shortly before five o’clock. During the return trip they had not seen a single person, even the keeper of the dam being away when they got there.  
“I don’t know about you, Bob, but believe me, I’m tired,” declared as he threw himself on his bed almost as soon as they had entered their cabin.
 
“I don’t feel exactly rested myself,” Bob smiled as he followed suit.
 
For half an hour neither again then a knock sounded on the door and Mr. came in.
 
“Well did you find the top of the mountain still there?” he asked.
 
“We didn’t get to the top,” Jack grinned.
 
“You didn’t?”
 
“No. You see we ran across what you might call unsurmountable obstacles, so to speak.”
 
“But what—”
 
“I’ll tell you all about it,” Bob interrupted, and proceeded to give him a full account of their adventures.
 
“Well, of all things,” Mr. Sleeper declared as he finished. “Why didn’t you call me on that radio set?”
 
“Well, you see, while we were tied up we couldn’t and after we got free and got our things back we figured that we’d better get away without any unnecessary delay,” Bob told him.
 
“But you say there was no way to get out of that cave except through the door?”
 
“I said we couldn’t find any. Of course there must be a way. A man can’t just naturally evaporate, you know.”
 
“No, but isn’t it possible that there was some place in the cave where he could hide?”
 
“It’s possible, of course, but we didn’t find any,” Bob assured him.
 
Just then the supper horn sounded and the boys hurried to wash up for the meal.
 
“Did you ever know a fellow called Skeets?”
 
Supper was over and Bob and Jack had followed Jacques out into the kitchen and it was Bob who asked the question.
 
“Skeets?” the breed repeated. “Heem big fellow wid long black hair and whiskers and nose , eh?”
 
“I don’t know what he looks like.” Bob replied. “But I heard him mentioned and just wondered if you know him.”
 
“Oui, me know heem. Heem one ter’ bad mans. Heem keel man two tree year ago, but no could prove, but me know.”
 
“Have you seen him lately?”
 
“Non, no seen heem most two year. Heem ver’ bad mans. Me no want see heem.”
 
“I would have liked to ask him if he knew about that cave but I didn’t dare to.”
 
It was shortly after nine o’clock and the two boys were alone in their cabin after a short sail on the lake with the .
 
“You were wise not to,” Jack agreed.
 
“I’m glad you think so,” Bob assured him. “You see we don’t know for sure just how he stands and until we do we’ve got to be careful. Not that I think he’s mixed up in it but, of course, there’s a chance.”
 
“You going to sit up tonight?”
 
“Not for all the ghosts this side of—of—”
 
“Of where?”
 
“Well, I guess I don’t know,” Bob laughed. “But it’s me for the hay.”
 
“Say, Bob,” Jack began a few minutes later after they had undressed, “If I ask you a question, promise me that you won’t jump down my throat.”
 
“I promise. What is it?”
 
“Has it ever occurred to you to wonder if the Sleepers are mixed up in this ghost business? Careful now. You know you promised.”
 
Bob had started up as though greatly surprised at the question, but he lay back again on the bed and for a moment did not answer.
 
“Well?”
 
“Just what made you ask that?”
 
“You answer my question first?”
 
“Yes.”
 
“Yes what?”
 
“It has occurred to me. Now what made you ask the question?”
 
“Because it occurred to me, I suppose. But you don’t think so, do you?”
 
“No. Do you?”
 
“N-o-o-.”
 
“You say that rather doubtfully.”
 
“Well, there’s one thing about it that I can’t quite make out.”
 
“And that’s?”
 
“It’s Mrs. Sleeper not being afraid of ghosts. Why yesterday she nearly fainted at the sight of an angle worm and she says she loves ghosts. It doesn’t fit in somehow.”
 
Bob made no comment for a few minutes then he said:
 
“Well, it’s no use saying that the same thing hasn’t been in my mind, for it has, but we must be very careful. The suspicion is far from being proof or even evidence, you know. By the way I intended to ask Jacques if any of the folks who had been seeing ghosts had mentioned about that spot of light. You don’t think that would do any harm, do you?”
 
“Don’t see why it should.”
 
“Well, we can ask him in the morning. Good night, sleep tight.”
 
“And don’t let the bite,” Jack finished as he blew out the light. Then he added: “If you see anything of that spot or any other ghostly , let me know, will you?”
 
In less than five minutes both boys were fast asleep. Whether or not the mysterious spot appeared that night they never knew for neither awoke until the breakfast horn rang out at half past six the next morning.
 
“See any ghosts?” Jack asked rubbing his eyes.
 
“Nary a ghost,” Bob replied as he jumped out of bed. “Come on, lazy, make it snappy or you’ll be late to breakfast.”
 
“Be dressed as—I say, Bob, what’s that paper on your bed?”
 
Bob looked quickly around and saw, on the foot of his bed, a sheet of paper folded once in the middle.
 
“Well, I’ll be jiggered,” he said a moment later, as he passed the paper to Jack. “What do you know about that?”
 
Jack took it and read:
 
“If you know when you’re well off you’ll leave
here before night.”
There was no signature to the message which was printed in crude letters.
 
“How’d it get there?” Jack asked as he stepped to the door and tried the lock. “This door is locked.”
 
“Are you sure?”
 
“Try it yourself.”
 
“But you know—”
 
“You’re wrong. I don’t know, any more than I know how that fellow got out of the cave,” Jack interrupted.
 
While he was talking Bob had been examining the window opposite the door.
 
“No marks of anything here,” he announced. “This screen doesn’t seem to have been moved.”
 
“Of course it hasn’t. You don’t think that ghost would be as clumsy as all that, do you?”
 
“But how—”
 
“Tell me how he got out of the cave and I’ll tell you how that letter got here—maybe.”
 
“But, Jack, this is serious.”
 
“You bet your life it is.”
 
“And I’m going to show it to Jacques and to the Sleepers and I want you to watch them closely when I spring it on them. We may get a clue.”
 
The other guests had not come in to the dining-room when they got there and Jacques was busy at the table. Bob handed him the paper without any word of explanation. The man looked at it, read it several times, turned it over to look on the back and finally turned to Bob.
 
“Whar you geet heem, eh?”
 
“It was on my bed this morning.”
 
“Huh! You keep heem door lock?”
 
“Yes the door was locked.”
 
Jacques scratched his head in evident perplexity.
 
“I dunno what tink,” he finally said. “What you do, eh? You go?”
 
“Not so you’d notice it,” Jack replied and as he spoke Bob fancied that a look of relief came to the breed’s face.
 
“Maybe you geet hurt you stay here,” he said, but in a tone in which Bob was sure there was only worriment.
 
“We’ll take a chance on that,” he said. “The fishing’s too good here to let a thing like that scare us away.”
 
“And it’s probably only a joke anyway,” Jack added.
 
Just then the Sleepers, including Helen, entered the room and after greeting them Bob showed them the note.
 
“You say you found this on your bed?” Mr. Sleeper asked after he had examined it closely.
 
“Yes,” Bob replied.
 
“And do you lock your door at night?”
 
“We have been doing it since we’ve been up here and it was locked this morning.”
 
“How about the windows?”
 
“There was no sign to indicate that anyone had crawled in,” Bob assured him.
 
“But do you think it would have been possible?”
 
“If you’d asked me that last night I’d have said no right off, that is without us knowing it, but that note didn’t get there without hands.”
 
“That’s true, of course. But what are you going to do about it?”
 
“Nothing, I reckon, except to keep our eyes open. You see we’ve been threatened before.”
 
“But aren’t you scared?” Helen asked anxiously.
 
“I never heard of a ghost hurting anyone, did you?” Jack laughed.
 
“But it wasn’t a ghost put that paper there,” she insisted.
 
“It’s rather strange that it should have been printed, don’t you think?” Mrs. Sleeper asked.
 
“You mean it looks as though whoever did it was afraid they would recognize the handwriting if it had been written?” her husband asked.
 
“Well it suggests that. Printing is a common way of avoiding recognition, you know.”
 
“True, but that suggests that it was done by someone whom they know,” Mr. Sleeper declared with a questioning glance at Bob.
 
“I see what you mean,” he answered, “but it hardly seems possible.”
 
“Well, how about it, Sherlock?”
 
Jack asked the question as soon as they were once more alone in their cabin.
 
“I don’t think Jacques knew anything about it,” Bob replied. “Do you?”
 
“If he did he’s a peach of an actor. No, I think he’s innocent. But how about the others?”
 
“Same verdict in my opinion.”
 
“Mine too. It would take a lot to make me believe that they are in it.”
 
“But I thought you said you—”
 
“I only said it seemed funny that she isn’t afraid of ghosts. I didn’t mean that I really suspected them,” Jack interrupted.
 
“Well, hurry up, there’s Helen all ready now.”
 
Helen and the two boys had, the night before, arranged a fishing trip up to a some six miles up the lake where Jacques had told them he had caught the largest he had ever taken from the lake, and soon they were speeding through the water, Bob at the stern of the canoe and Jack in the bow, with the girl between them. It was a beautiful morning clear and cool and, despite the threatening letter, they were all in high spirits.
 
“What kind of fly had I better use?” Helen asked when they had reached their destination.
 
“I’m afraid flies wouldn’t be much good here, not at this time of year,” Bob explained. “You see the water’s very deep here and the fish feed near the bottom, so we brought along some shinners.”
 
“Then we’re going to troll?”
 
“Yes, it’s the only way to get the big fellows this late in the season. In May and early June they’ll take a fly all right.”
 
“Mercy, are you going to on all that lead?” she asked a moment later as Bob took some heavy sinkers from his pocket.
 
“Have to keep your hook down near the bottom, in fifty feet of water,” he explained.
 
Quickly the lines were made ready and soon Bob was using his paddle just enough to keep the canoe barely moving, while he held his rod between his legs.
 
“Let out about a hundred feet of line,” he told her.
 
“Do they bite very hard?” she asked.
 
“Not very. You see a laker is not much of a fighter. A three or four-pound square tail will put up more of a fight than a twelve-pound laker. You can usually pull the latter in without playing him at all. But you’re apt to get hold of a and then look out. They’re gamey enough.”
 
He had just finished speaking when the girl’s rod bent sharply. “I’ve got one,” she cried.
 
Bob stopped paddling. “Reel him in if he doesn’t pull too hard,” he ordered.
 
“I guess he’s only a little one,” she declared a moment later after she had recovered about half of her line.
 
“You never can tell,” Bob cautioned as he picked up the landing net. “Be on your guard for a rush though I hardly think he’ll make one.”
 
“He’s pulling harder now,” she said and he could see that she was having about all she could do to turn the handle of the reel.
 
Foot by foot the line came in and finally Bob declared that he could see the fish.
 
“Steady now,” he cautioned. “Just a little more and I’ll have him.”
 
Followed a swift thrust of the net and the fish was in the canoe.
 
“Gracious, he isn’t so small after all,” Helen cried.
 
“About eight pounds and two and a half feet long,” Bob said as he hit the fish on the head with a small stick putting an end to its struggles.
 
“You were right when you said they weren’t fighters. Why I’ve had more trouble landing trout not a third as large.”
 
“But he’ll make up for it when you eat him,” Jack laughed.
 
Bob started the canoe forward again as soon as he had put a fresh shinner on Helen’s hook. They had gone only a few yards when Jack announced that he had a strike and as Bob glanced back he saw a of silver break through the surface of the lake, rise a foot above the water and fall back with a loud splash which could be plainly heard.
 
“You’ve got a salmon and a big one, boy,” he shouted. “Play him easy or you’ll lose him.”
 
Jack was reeling in as fast as his multiplying reel would permit but before he had the fish half way to the canoe a sudden rush jerked the handle of the reel out of his fingers and before he could apply the drag nearly all his line had disappeared.
 
“Back her up,” he shouted to Bob, pressing the drag as hard as he dared. “This line’ll never hold that whale.”
 
Bob was quick to grasp the situation and just as the last few layers of line were leaving the reel, the canoe began to move in the direction the fish had taken. This relieved the strain so that Jack was able to recover a few precious yards before a new rush in the opposite direction nearly jerked the rod from his hands.
 
“T’other way quick,” he cried.
 
Again Bob was able to get the canoe in motion in time to save the last few feet of line, but the manoeuver had to be repeated, with many variations, several times before the big fish was finally conquered. But after nearly an hour of battle he succeeded in bringing the fish within reach of the landing net and in another moment it was safe in the canoe.
 
“My, what a fish!” Helen . “How much will it weigh? About a hundred pounds?”
 
“Not quite, I’m afraid,” Bob laughed. “Knock off about eight-five and you’ll be pretty near it.”
 
“It’s your turn now,” Jack declared as the canoe began to move again. “Better let me play engine for a while so you can—what was that?”
 
“What was what?”
 
“Didn’t you hear that twang?”
 
“No, I didn’t hear anything. You—”
 
But at that moment a slight splash a few feet to the right of the canoe caused him to turn his head. There, floating lightly on the water, was an arrow. For an instant the two boys looked at each other.
 
“What do you know about that,” Bob gasped.
 
“I told you I heard a bow string twang.”
 
“But this is Maine and in the twentieth century.”
 
“Look,” Helen suddenly cried, “There’s a piece of birch bark fastened to it.”
 
Another moment and Jack was removing the bark which had been tightly bound to the just above the feathered end. Carefully he smoothed it out and bent his head to examine it. Scratched on its surface, evidently with some sharp instrument, were two words: “second warning.”
 
He handed the piece of bark to Bob without a word.
 
“May I see it?” Helen asked after Bob read it.
 
He handed her the bark saying: “Looks as though someone was trying to scare us.”
 
“Of course the one who put that note on your bed is responsible for this as well,” she declared after a moment’s thought.
 
“I guess there’s not much doubt about that,” Bob agreed and Jack nodded his head.
 
“What are you going to do about it?” she asked.
 
“Nothing, except that I think we’d better get back to camp as soon as we can,” Bob replied with a at Jack which he evidently understood for he seconded the motion at once.
 
“But what’s the hurry?” Helen asked.
 
“Well, you see,” Bob explained, “whoever shot that arrow might take it into his head to shoot at us and he evidently’s a pretty good shot even with a bow and arrow.” He was aware that the explanation was pretty weak but it was the best he could think of on the spur of the moment. Helen looked rather puzzled but offered no objection as they began to reel in their lines.
 
If she was surprised at the speed with which they sent the light canoe through the water on the way back she said nothing about it, except to caution them a couple of times to be careful or the of the water might set the craft on fire. As they rounded a point of land which stretched far out into the lake, and came in sight of the little in front of the camp both boys breathed a silent sigh of relief as they saw the two Sleepers together with Jacques just putting out in the motor boat.
 
Helen shouted and waved her hand at them and Jacques shut off the engine which he had just started.
 
“You’re back earlier than we expected,” Mrs. Sleeper said as the canoe drew up alongside. “We were just going up to see how you were making out.”
 
“Oh, we made out all right,” Helen told her, holding up the salmon by its gills. “How do you like this fellow?”
 
“Mercy, is it a whale?” her mother asked.
 
“Not quite,” Helen laughed.
 
“Did you catch it?”
 
“No, but I caught this baby,” and she held up the trout for their . “Jack got the big fellow.”
 
“I didn’t know they grew that large in the lakes of Maine,” Mr. Sleeper said as he reached over and picked up the salmon. “This fellow must weigh all of twenty pounds.”
 
“Heem weigh fourteen, mebby fifteen pound. Bon feesh but some bigger in here,” Jacques told him.
 
“Well, I’m not going to be cheated out of my sail,” Mrs. Sleeper declared. “It’s not quite eleven yet and we’ll have time for a short one before Jacques has to start dinner. Anyhow, if it’s late it’ll be all right as we’re the only ones to please. Come on Helen and you too, boys.”
 
The boys were anxious to be alone in order to compare notes, but they could not well refuse the invitation so they accepted with no show of . They were gone for an hour and it was but a little past noon when they were back in their own cabin.
 
“Well, I reckon that lets ’em all out, eh?” Jack asked as soon as he had closed the door.
 
“So far as that arrow is concerned, yes,” Bob agreed. “Whoever shot it couldn’t have got back here in the time we made, unless he had an airship or something of the sort. No, there’s somebody else, but whether or not any of them are mixed up in it is another question.”
 
“And one which we ought to be answering before long. We know just about as much about the matter as we did before we came up here.”
 
“And not much more. That’s a fact, but I hardly see how we could have done any more than we have. I tell you, son, whoever’s at the bottom of this game is deep, mighty deep.”
 
They talked until the dinner horn rang through the forest and on a course of action which they hoped would be productive of results.
 
“Did you save that piece of bark?”
 
They had joined the Sleepers in the big diningroom and it was Mr. Sleeper who asked the question. “Helen has told us about it,” he added as Bob reached in his pocket and drew it out.
 
He examined it carefully and then passed it to his wife.
 
“Do you think it is from the same party?” she asked, then, turning to the boys, she added: “Mr. Sleeper is quite an expert on hand-writing.”
 
“I don’t think there’s any doubt about it,” he said at once adding: “Of course, it would be impossible to say that both were printed by the same person so far as the printing itself is concerned since one is on paper and the other on birch bark, but it’s hardly likely that there are two parties up here in the woods trying to scare the boys.”
 
“I think you’re right, sir,” Bob agreed.