This plan was agreed upon, although reluctantly on Bess's part. George offered to drive back to town and tell Mrs. Hosking of the girls' change in plans.

"In the meantime, I'll make up some beds," Bess offered.

"And if you don't mind," said Nancy, "I'd like to do a little investigating outdoors."

Bess warned her to be careful. Nancy said she would not go far. "Just down to Henry Winch's dock."

She rode that far with George, then got out of the car and went down a path to the dock. To one side of it was a good-sized boathouse, and with moonlight streaming into the windows, Nancy could see motorboats, rowboats, and canoes. On the other side of the dock was the confectionery store with Mr. Winch's living quarters behind it. From the end of the dock, Nancy had a clear view of the whole lake-cottages, the large house on the bluff, and the mist-shrouded end of the lake.

The young sleuth smiled to herself. "I wish that phantom boat would appear! I'd like to know what it looks like."

But there was no sign of any ghostly vessel, and finally Nancy walked back to the cottage along a path near the lake front. She heard a car coming and wondered whether it was George returning, or Cecily Curtis arriving. She hurried up to the road to find out.

The car proved to be her own and in a moment George alighted. She had brought a few supplies which Mrs. Hosking had given her for the girls' breakfast.

"I insisted upon paying her for the food," said George, "and also a fair amount for holding our room."

"I'm glad you did that," said Nancy.

"We'd better take our bags," said George. They took them from the trunk, locked the car, then the two girls started in silence down the wooded path. They were about halfway to the cottage when suddenly they heard soft rustling in the bushes at the top of the slope above. The next moment something black shot past them!

The girls jumped, wondering what the object was.

"Some animal, I think," said Nancy. "We must have scared it."

The words were hardly out of her mouth when a high, clear voice called, "Satin, come back here!"

Nancy and George turned. Someone was starting down the path. It must be Cecily!

The two girls set down their bags and started forward to greet her. Nancy called out "Hello," as she beamed her flashlight up the hill.

The girl from the White Mill restaurant again! But this time she was not wearing the raincoat and scarf. She had on the same outfit they had seen at the restaurant, and was lugging two suitcases.

"Oh, hello!" she said pleasantly. "Well, this is a nice surprise! Are you vacationing here?"

Nancy and George were confounded. Hadn't the newcomer recognized them? And why had she changed her clothes again?

"Are you Cecily Curtis?" Nancy asked as the girls hastened to help her.

"Yes, I am. But how did you know?"

Nancy, though bewildered, decided to ask no questions, but she did notice the girl was not yet wearing a wedding ring. She introduced herself and George. "Mr. Winch is out of town, so we came here with the key to open the cottage for you."

"How wonderful!" Cecily said.

"What is Satin?" George asked, taking one of the bags.

"My big black cat. I dropped his carrying case and it opened. He zipped out of it like lightning."

Nancy chuckled. "He flew right past George and me."

Cecily stopped short. "I just recognized you both! It was so dark and I was so startled I didn't realize I'd met you at the White Mill. Imagine! Especially after you rescued me, Nancy! But there were three of you. What happened to the other girl?"

"Bess Marvin is in the cottage making up beds." Nancy smiled. "Now that you are here, though, we'll go back to town for rooms."

"Oh, I'd be delighted to have you stay," Cecily declared. "Really, I would! To tell the truth, I'm pretty lonesome."

"We'll accept with pleasure!" said Nancy.

By this time the three had entered the cottage. At once Bess exclaimed, "I'm so glad you got here, Cecily! We were terribly worried. Why didn't you stay the first time you came?"

Cecily looked at her blankly. "The first time? I haven't been here before."

It was Bess's turn to look perplexed. "You mean you weren't up in the woods on your way here a few hours ago?"

Cecily shook her head. "If you thought you saw me, I must have a double in the vicinity." She changed the subject. "I had an awful time getting to this cottage. A bus brought me to Misty Lake village from Baltimore, and I tried to get a taxi to bring me here. Nobody wanted to, but finally one man agreed to drive me as far as the end of the lane. I had to lug these bags and my cat all the rest of the way."

"You poor thing!" Bess said sympathetically.

Nancy, Bess, and George had agreed tacitly not to mention having overheard Cecily and her fiance talking. If she felt like telling them, however, they would be interested listeners!

Nancy said, "Don't you think we'd better find Satin?"

Cecily nodded, and the four took flashlights and went outside. Nancy gave the key to Cecily, who locked the cottage door. The girls began the search. Cecily kept calling the cat by name, but he did not come.

"Oh, dear!" Cecily sighed. "Satin is such a comfort to me. I shall just die if he is gone."

Without being sure where to look next, the girls finally turned right. They passed the neighboring cottages, then Henry Winch's dock and continued along the lake front toward the stone house, atop the bluff. Cecily kept calling softly to her pet. Finally George spotted two glowing eyes peering from behind a tree and whispered to Cecily, "I'll bet that's Satin!"

"Here kitty, kitty, kitty!" Cecily said quietly. "Come here, Satin!"

Reluctantly, the big black cat came toward her. She scooped him up in her arms and patted him affectionately.

Through the stillness of the woods, Nancy detected a strange sound. "Listen!" she said quickly.

They all stood motionless. Amid the chirps of myriad crickets and the hoots of an owl, the girls could hear a steady humming noise. It was not far from them. What could it be?

CHAPTER IV.

The Wailing Cry

THE girls listened intently as the strange humming noise continued. It was muffled.

"That must be a machine," Nancy remarked. "But what kind and where is it?"

"It's probably just a pump," George said practically.