towered above this trestle. Altogether the deck of the yacht was fully twenty feet from the ground. They ascended and descended by means of a rope ladder. This ladder, at the present moment, lay on the deck. No one could enter their cabin unless he were possessed of a ladder and any person attempting this would at once be detected and might be arrested for it, so why be afraid?

But, after all, that sound was puzzling. She wanted to know what it meant. For some time she contemplated slipping on her dressing-gown to creep out on deck and peer over the side. But the wind was chill and still rising. The flag-rope was whipping the mast with ever-increasing fury.

“Cold out there,” she thought with a shiver. “Glad the O Moo is in dry dock and not on the water!”

A sudden thought brought a new fear. Of a whole line of schooners and yachts on that track in the dry dock, the O Moo was the one closest to the water. What if she should slip back into the water and be driven out into the lake! Lucile shivered again. Then she smiled. How absurd. Did not a heavy cable hold her in place? Were not the wheels of the car, on which she rested, blocked? How then could she glide back into the lake?

Fortunately, it did not occur to her that this very tap-tap-tapping might be the knocking of a hammer which was driving those blocks from their positions before the wheels of the car.

Since this thought did not come to her and, since the tapping did not come again, she at last snuggled down among the blankets and fell asleep.

Hardly had she wakened in the morning before she recalled this strange incident of the night. Hurriedly slipping into a middy suit and slippers, she raced up the short gangway and across deck, tossing the rope ladder over the side. The next moment she might have been seen walking slowly about the hull of the yacht. She was searching for traces of the strange tapping.

Having passed along the south side, she climbed through the trestle and made her way along the north side. She was about to conclude that the night’s experience had been purely an imaginary one when a white spot near the prow attracted her attention.

She caught her breath as her hand reached for it. It was a square bit of paper held in place by four tacks which had apparently been driven into the hull with great deliberation.

“That explains the tapping,” she whispered to herself. “Sure had their courage right along with them. Thought we’d be afraid to interfere, being just girls, I suppose. Wonder what it is.”

She reached up and pulled the paper free from the tacks. As soon as she had it in her hand she realized that written on it was a message. She read it—read it twice—then stood there staring.

The paper was of a peculiar rice-straw variety. The words were written in a strangely artistic fashion. Fine as the tracing of a woman’s pen, each letter stood out distinct, done in curves of wonderful perfection, the work of a master penman.

But she did not pause to admire the handwriting; it was the meaning of the words that startled her as she read:

“You must not stay here. You shall not stay. I have said it.”

It was signed only with a crosslike figure, a bizarre sketch that might well have represented the claw of a bird—or a dragon, Lucile added with a little intake of breath.

“I must show the girls,” she exclaimed, and nimble as a squirrel, was away over the trestle and up the rope ladder.

When the other girls had heard Lucile’s story and had read the note they were more astonished than alarmed.

“Huh!” exclaimed Florence, gripping an iron rod above her and lifting her full hundred and sixty pounds easily with one hand. “Who’s telling us whether we can stay here or not?”

“I’d say they better not let you get near them,” smiled Lucile.

Florence laughed and, releasing her grip on the rod, sat down to think.

“Doesn’t seem possible it could be anyone living in the other boats,” she mused. “I’ve seen that young man they call Mark Pence, the fellow who lives in the gasoline schooner, just once. He seems to be decent enough.”

“And the old fishermen,” put in Marian, “I hired two of them to pose for some sketches last week. Nice old fellows, they are; a little rough but entirely harmless. Besides, what difference could it make to them whether we live here or not?”

“There’s the Chinamen who run a little laundry in that old scow,” said Lucile thoughtfully, “but they are the mildest-mannered of them all, with their black pajama suits and pigtails.”

“And that’s all of them, except Old Timmie and his wife,” said Florence, rising and pressing the lever which brought the electric range into position. “And as for Timmie, I’d as soon suspect my own father.”

“We’ll tell him about it,” said Lucile. “He might help us.”

They did tell Timmie, but he could throw no light on the subject. He appeared puzzled and a little disturbed, but his final counsel was:

“Someone playing a practical joke on you. Pay no attention to it. Pay no attention at all.” The girls accepted his advice. Indeed, there was nothing they could do about it.

“All the same,” was Lucile’s concluding word, “I don’t like it. Looks as if someone in this vicinity were doing something they should not do and were afraid we’d catch them at it. I for one shall keep an eye out for trouble.”

The other two girls agreed with her, and while they did not alter their daily program in the least, they did keep a sharp lookout for suspicious characters who might be lurking about the dry dock.

CHAPTER II
THE BLUE FACE IN THE NIGHT

Lucile need not have kept an eye out for trouble. Trouble was destined to find her and needed no watching. As she expressed it afterward: “It doesn’t seem to matter much where you are nor what you are doing, if you are destined for adventures you’ll have them.”

But the thing which happened to her on the following evening, though doubly mysterious and haunting in its character, appeared to have no connection whatever to the incident of the note.

The storm which had been rising all night had lulled with the morning sun, but by mid-afternoon was raging again with redoubled fury. Sending the spray dashing high above the breakwaters, it now and then cast a huge cake of ice clear of the water’s tallest crest and brought it down upon the breakwater’s rim with the sound of an exploding cannon. Carrying blinding sheets of snow before it, the wind rose steadily in force and volume until the most hardy pedestrian made headway against it with the greatest difficulty.

When Lucile left the university grounds to face east and to begin forcing her way against the wind to the yacht, night had fallen. “Dark as it should be at seven—woo! what a gale!” she shivered, as buttoning her mackinaw tightly about her throat, she bent forward to meet the storm.

For a half hour, her body beaten and torn by the wind, her face cut by driving sleet, she fought her way onward into the night. She had reached the shore of the lake and was making her way south, or at least thought she was. So dense was the darkness that it was with the utmost difficulty that she kept her directions.

“Wish—wish I had tried getting a place to stay nearer the university,” she half sobbed.

As if in answer to these words, the storm appeared to redouble its