Nancy also decided that it was possible the machine that made the humming noise was in this very same passageway! But what was the machine for? Her mind went back to the counterfeit idea.

"Oh, dear, if I could only find out!"

At that very moment she heard a ship's bell ring. The girl detective stood stock-still, listening. The ringing continued for about a minute. Then suddenly in the fog at the end of the lake, the phantom launch appeared!

"This time I'm going to find out what's going on!" Nancy determined.

Leaving the dock, she sped to the Baker cottage. She pounded on the door, calling, "Quick, Cecily! Let me in!"

Cecily dashed to the door and opened it. "What's the matter?" she asked.

"The phantom launch! Look!"

Cecily stepped to the porch and stared at the weird sight. Nancy, meanwhile, grabbed a paddle. "I'm going to try and find out what it is!" she cried, and rushed down to the canoe.

Nancy turned it over, pushed the craft into the water, and jumped in. She began to stroke furiously toward the phantom boat.

The shortest route was by the center of the lake where the water was deepest. The canoe glided forward at racing speed. Nancy had been so intent upon the sight ahead that she failed to notice the craft was leaking. Now she felt her ankles getting wet and looked down in dismay. Water was pouring into the canoe.

"What horrible luck!" Nancy murmured in disgust. "Just when I had the mystery in my grasp."

All the young sleuth could do was gaze ahead and try to get as clear a picture of the phantom launch as she could.

Suddenly a black cloud blotted out the moon. When it reappeared, the launch had vanished, and within seconds, the canoe sank!

CHAPTER XIII.

A Spy?

STILL clutching her paddle, Nancy started to swim for land.

"I'm sure I couldn't rescue the canoe. It will have to be fished out of the bottom of the lake."

As Nancy neared shore, she began to wonder whether someone was waiting in ambush. There was no doubt in her mind that the canoe had been sabotaged! It had been all right when Henry Winch left it.

"Could it be the work of the Driscoll brothers?" she asked herself, and clutched the paddle tighter. "If anybody tries to waylay me I'll use this as a weapon!"

Before leaving the water, Nancy looked up and down the narrow beach, at the foot of Pudding Stone Lodge. There was no one in sight and finally she stood up and waded ashore. A chill breeze struck her and she began to shiver.

"Great!" Nancy said to herself. "Whoever my enemies are they're tricky. It never occurred to me that anyone would tamper with the canoe."

Partly to keep from being seen and partly to keep out of the wind, Nancy went up to the path that led through the woods and headed for the cottage.

"If I weren't so uncomfortable and didn't have so much on my mind," Nancy thought, "I could really enjoy this gorgeous moonlight and scenery."

Suddenly, as she rounded a bend in the path, she saw a girl ahead.

"Cecily!" she cried out.

Instead of answering, the young woman fled up the hill among the trees. Nancy knew now that she was not Cecily but the other red-haired girl.

"Please wait! I want to talk to you!" she called. "I'm not going to harm you."

The fleeing girl paid no attention. Soon not even her footsteps could be heard. Where had she gone? To Pudding Stone Lodge?

Nancy became lost in speculation as she went on toward the cottage. Maybe she was wrong about the strange girl. If the young woman was afraid to speak to Nancy, she might well be a spy for the Driscolls-not a prisoner! Possibly she had been posted near the girls' cottage that evening, to follow anyone who came out.

Nancy pursued her line of reasoning. "As soon as I set off in the canoe she could have run along the path, to see what happened to me. When the canoe filled with water and I began swimming, she knew I wasn't going to drown. She waited to see what I'd do when I got to shore. The instant I called out Cecily's name, that girl rushed back and reported everything to the Driscolls."

Another idea occurred to Nancy-that someone wanted to keep people from getting too close to the phantom ship, so he had sabotaged her canoe.

By the time Nancy reached the cottage, she was cold and exhausted. She saw smoke coming from the fireplace chimney and took heart at the thought of its cheering warmth.

As Nancy opened the door and walked in, she saw Bess, George, Cecily, and Niko grouped around a roaring fire.

"Nancy! Whatever happened to you?" Bess cried out, upon seeing the bedraggled, shivering girl.

Her friend normally would have given a humorous answer, but instead she said seriously, "Hello, Niko! I'm glad to see you again. As for me, somebody put a hole in the canoe and I took an unexpected bath."

"Who would have done that?" George asked. "Oh, don't tell us now, Nancy. You get yourself into a hot bath pronto!"

Nancy was glad to obey. Later, while she was dressing, Bess and George came into her room. They had decided to retire, and leave Cecily and Niko alone to talk over their problems.

"Nancy," said George, "we were just about to send a search party out for you. Now, give us the details."

When Nancy finished her story, the cousins shook their heads ruefully. Bess said, "This mystery gets more dangerous all the time for you, Nancy. And here you are worrying about losing the canoe! It's just lucky you weren't drowned! I honestly don't think your father or Mrs. Gruen would want you to take such chances."

The young sleuth smiled. "But I never know when I'm going to have to take chances!" she countered. "I just know that any time I undertake a case, I'm apt to run into some kind of a trap."

"I suppose you're right," Bess conceded. "But I'm going to do my best to keep you out of any traps from here in!"

"Thanks, Bess," Nancy said with an affectionate look at her friend. "And now, about that other red-haired girl. I have two completely opposite ideas about her. One is that she is in cahoots with the Driscolls in some underhanded scheme; the other is that she's their prisoner or is somehow in their power. For example, it might be she managed to escape tonight. But she thinks that I am working with the Driscolls and only wanted to delay her so she could be recaptured."

Bess sighed. "You're going too fast for me, Miss Detective."

George spoke up. "For that matter, I wonder how other facets of the mysteries may involve this strange girl-such as the phantom launch, the peculiar humming noise, and even the treatment those poor twins are apparently getting!"

Bess shook her head. "I can't tax my brain any more tonight. Say, I'm starved! How about the three of us transferring to the kitchen for a midnight snack?"

Nancy chuckled. "To tell the truth, I think a little food would completely revive me. I've worked up an appetite by my long swim and hike."

Bess, the culinary expert, was out of the door by this time and heading for the little kitchen. The others followed.

"Well, what shall it be?" Bess held up a spoon and struck a chef-like pose.

"Hot tomato soup," said Nancy, "with cream in it."