Through the soft, impenetrable darkness stole the almost inaudible sound of a paddle, and strangely enough, only a single stroke was heard. The listening youths agreed that the point whence it came was to the north of the islet, and it was Chester Haynes who was keen witted enough to hit upon the explanation.

"Whoever it is he is trying not to betray himself; he is using his oar as a paddle, to avoid the sound of rowing."

"But we heard him," said Alvin.

"He made a slight slip and may do it again."

They listened intently for several minutes, but the stillness was unbroken. This continued for some time, when suddenly the sound was heard, fainter than before—so faintly indeed that had not the two been closely attentive they would not have noted it.

"Another slip," remarked Chester; "I guess he doesn't know how to handle a paddle very well. But he has got ahead, for he isn't where he was when we first heard him."

"He seems to be between us and the islet."

"He may be coming this way!"

As if in answer to the thought, the few rays of moonlight which fell upon the water at that moment revealed the dim outlines of a small boat that was heading toward the very spot where the friends were standing.

"Let's make a change of base," whispered Chester, hastily turning to the north, but halting where they could see the boat without being visible themselves.

With the weak light, they could trace it quite clearly. The craft was of the ordinary structure, so small that it would not have carried more than two or three persons, and had nothing in the nature of a sail.

A man was seated in the middle holding a single paddle which he swayed first on one side and then on the other. The observers suspected his identity before the nose of the little boat slid up the bank and it came to rest. Gently laying down the paddle, as if guarding against discovery, the man rose to his feet and stepped out. As he did so, he grasped a small handbag in one hand and moved with the alert nimbleness of a boy. He was the man in the gray suit, who seemed to have formed the habit of intruding into the plans of Alvin and Chester. They waited motionless and silent until he disappeared in the wood.

"Chester," said his friend, "I'll give you eleven cents if you will explain that."

"And I'll give you twelve if you'll clear it up for me."

"I wonder now if he isn't acting as a sentinel for the others. He knows we are somewhere in the neighborhood and has set out to keep track of us."

The theory might seem reasonable to the boys, but would not hold water, for, after all, the action of the stranger did not agree with it. They felt it idle to try to guess, and gave it up. Alvin had proposed that they should stay no longer in the wood, but return to the hospitable home of Uncle Ben. Though it would be late when they reached there, they would be welcome, but both shrank from meeting the couple after the discovery of the money they had placed under their plates.

"Hold on, Alvin," whispered the other; "let's play a trick on that fellow that keeps nosing into our business."

"How?"

"Let's use his boat to get a closer view of the Deerfoot."

It was a rash thing to do, but it appealed to the young Captain.

"All right; I'm with you. We must hurry, for he is likely to come back any moment."

Had they taken time for reflection, they probably would have given up the plan, but boys of their age and younger are not apt to "look before they leap." Without hesitation, they walked to where the frail boat lay against the bank and Alvin shoved it clear. The water seemed to be deep close to land, and the Captain took up the paddle, remarking that the craft bore some resemblance to a canoe. They half expected that the man would dash forward and call them to account, but nothing was seen or heard of him, and the gloom swallowed them from sight of any person on land.

Now that the chance was theirs to settle the question which had perplexed them so long it was important to consider each step. Alvin had had experience in managing a small boat and he handled the paddle with more skill than the former occupant, for the ripple which he caused could not have been heard a dozen feet away. As the distance from shore increased, they ceased to whisper. One knew the right thing to do as well as the other, and Chester realized that he could give no directions of value.

It seemed to Alvin that since those on the launch knew the direction taken by one of their number, they would expect him to return over the same course. Instead, therefore, of making straight for the motor boat, the Captain turned to the right, so as to approach the bow or stern. Before he caught sight of the craft, he made a complete circuit of the islet, keeping just near enough to trace its outlines and that of the launch. The former was merely a mass of sand, consisting of about an acre and without a tree or shrub upon it. It must have been nearly submerged when the tide was high.

Seated in the prow of the small boat, Chester Haynes peered with all the power of eyesight at his command into the darkness, partly lighted up now and then by the moon. This made the illumination treacherous and uncertain and caused misgivings to both. Alvin glanced up at the rolling clouds, striving to avoid betraying himself to anyone on board. The presumption was that all had gone to sleep, leaving the duty of protection to their friend, the man in gray.

A look at the masses of vapor in the sky told Alvin that the heavy obscurity would last for several minutes. He dipped the paddle deeper and stole toward the bow of the launch that was beginning to show vaguely. By and by he saw the sharp cutwater rising several feet above the water, the staff with its drooping flag, and the glass shield just aft of the motor compartment.

"Sh! sh! back quick!"

Chester whispered the warning, and Alvin without pausing to ask the reason swung the paddle so powerfully that the gentle forward motion was checked, and the boat moved in the other direction. Two or three strokes carried it so far that the launch and all pertaining to it were swallowed up in the gloom.

Waiting till it was safe to speak, the Captain asked:

"What did you see, Chester?"

"A man," was the reply.

"In what part of the launch?"

"He was standing in front of the cockpit, about half way between it and the flagstaff."

"Then he saw us."

"No; for he was looking toward the shore to which this boat had gone. Had he turned his head, he must have noticed us."

Alvin held the reverse motion until they felt it safe to talk without dropping into whispers.

"What harm could have come if he had seen us?" asked the Captain, "I favor going straight up to the Deerfoot, stepping aboard and ordering the thieves to turn her over to us."

"Before doing so, one thing ought to be settled."

"What is that?"

"Find out whether it is the Deerfoot."

"Of course it is; what other boat could it be? We act as if we were afraid to claim our own property."

"Your property you mean, Captain. If I may advise, it is that you make another circuit around the islet and come up to the launch from the rear. I don't think there is a second man on watch, and, if there isn't, we shall be less likely to attract the first one's notice."

"I'll do as you say, though I see no sense in it."

With the utmost care the islet was circumnavigated as before, and the stealthy approach from the rear was made. Alvin depended upon his companion to give him warning, and while he remained silent the small boat glided forward like a shadow cast by the moon.

The man who had been seen standing near the prow would have been in sight had he held his position, and since he was invisible, he must have gone away. With the acme of caution, Alvin stole along the side of the launch, keeping just far enough off to avoid grazing her, until he came once more to the bow.

This period being one of the total eclipses of the moon, he could do no more than trace the outlines of the boat, whose familiar appearance filled him with burning indignation that thieves should have dared to lay hands upon it. There was not a breath of air stirring, and Chester who still clung to his doubts, now drew his rubber safe from his pocket and scratched a match over the corrugated bottom. As the tiny flame flickered, he held it up in front of the gilt letters on the side of the prow. Each saw them plainly, long enough to note that the name painted there was not Deerfoot but Water Witch!

Alvin was astounded and disgusted beyond expression. Without a word, he turned the head of the little boat toward the shore which they had left a short time before, and did not speak until they reached land. He was impatient, because he plainly heard his companion chuckling.

"Let's give up looking for the Deerfoot," exclaimed the Captain, "and see whether we can find Mike Murphy."

"I'm with you," was the hearty response of Chester.

Indeed it is high time that we, too, started upon the same errand.