Nancy suggested that the whole affair should be reported to the State Police in the morning, and offered to do it for Theresa. She asked Art if he would take her into town directly after breakfast to phone headquarters.

"Glad to," he replied. "Good night."

Nancy and Julie Anne went back to bed and slept soundly until Theresa rang the rising bell. When the other diggers learned about the night's adventure, they were alarmed. Theresa tried to calm their fears, but she herself was concerned. Why was her expedition being bothered?

Nancy was sure she could read the woman's thoughts. Going up to her, she said quietly, "You weren't having any trouble here until I arrived. My mystery must be the cause of it. I can't figure out how the hollow oak I'm looking for and your dig are connected but there must be some tie-in. I'm sure Kit Kadle is trying to discourage my sleuthing. It would be better if I leave. Then no one will be in danger."

Theresa put an arm around Nancy's shoulders. "You're going to stay," she said firmly. "What you say may be true, but as yet we have no proof. Besides, we like having you at the dig. I won't hear of your leaving."

Nancy thanked the leader and kissed her. "In any case, Art and I will report last night's episode to the State Police, if you wish us to."

"Yes indeed."

They rode away on the motorcycle and soon reached Walmsley. Nancy telephoned the State Police, who promised to investigate at once. Next she called her father. "Dad, I'm so glad I reached you. How's everything?"

"Just fine, but Hannah and I miss you very much. Well, what's the report on the mystery?"

Nancy brought him up to date. Then Mr. Drew told his daughter that Ned Nickerson was very eager to get in touch with her. "I suggest you call him."

Nancy did this, trying three different places where she thought Ned might be. But he was not at any of them. Nancy sat in the phone booth another half a minute thinking of the tall, good-looking young man. Right now he was working on a summer job, selling insurance.

"I wonder," she thought, "if by any chance Ned is going to tell me he's coming out here." She hoped so!

Art came to see if she was ready, saying he must get back to the dig. The two roared off on the motorcycle. As they approached the farmhouse, they noticed that two state troopers were already there. With them was an elderly Indian.

Nancy dismounted and walked up to the group. She introduced herself. The troopers gave their names as Rankin and White, and introduced the Indian as Robert Lightfoot.

"Mr. Lightfoot is the one who built this ladder," Rankin said, pointing to the crude piece which lay on the ground beside them. "I've seen others like it at his cabin. He says a man who didn't give his name came to his place and wanted to buy the ladder."

The Indian took up the story. "He was a stranger. Told me he needed the ladder to prune his apple trees."

"This time of year?" Trooper White exclaimed. "That's crazy!"

Lightfoot smiled. "I think so too."

Nancy asked for a description of the man. Upon hearing that he was lame and gray-haired, she was sure he was the same person who had brought the ladder to the excavation. The Indian was amazed to learn this and said the buyer had not mentioned the dig.

The troopers walked off a little distance for a private conversation. Nancy took the opportunity to ask Lightfoot if he had heard the legend about Pere Franois and the hollow oak.

"The missionary's treasure will never be found around here," Lightfoot replied.

"Treasure?" Nancy repeated.

"Maybe you think there was only a message," the Indian went on. "The message told about the treasure. Pere Franois was captured by the Iroquois but he escaped. He started for the Ohio River but never got there. River pirates stole the treasure he was carrying. I am sorry to say they killed him."

"Did the legend tell what happened to the treasure?" Nancy asked.

Lightfoot nodded. "The pirates took it to the river and hid it somewhere. I think maybe in a cave. Nature punished the pirates for their thievery. A great storm overtook them and all were drowned."

Nancy was intrigued by the story. "Then the treasure might still be hidden in the cave?"

"It could be," the Indian answered.

The two troopers came over and said they must leave. They promised to start tracking down Tom Wilson. Lightfoot left with them.

As Nancy went for her digging tools, she kept thinking about the message in the hollow oak, the legendary treasure and its hiding place. Was it possible the pirates' loot could still be there?

"I'd like to hunt for it," she said to herself. But her thoughts were interrupted when she unearthed a tiny bone. A little later she was delighted to come upon another which matched it. Theresa was thrilled.

It was not until evening that Nancy had a chance to tell Theresa about the Indian's story. The archaeologist was interested. She remarked that it was possible to go up and down the Ohio River by towboat and barge.

"While you're here, perhaps you'd like to arrange for a trip," she suggested. "You get on at Cairo."

"I'd love to," Nancy said. "Tomorrow Clem is coming to take Julie Anne and me on another search for the hollow oak with the message. If we don't find anything, perhaps it would be worth looking in caves along the river."

"The most likely one for pirates to have used would be Cave in Rock," said Theresa. "It's on the Ohio River near Elizabethtown, Illinois. For a number of years after the Revolutionary War outlaws and pirates used that cave as headquarters. From there they preyed on the flatboats carrying pioneers down the river. Now it's part of a state park."

"It sounds fascinating," said Nancy.

The next morning Clem's car rattled into the farmhouse yard. Nancy and Julie Anne were waiting with a box of lunch. Clem was cheerful as usual and full of exaggerated stories about the area. Right after he had related one about a pioneer who always shot with two guns crossed, Nancy asked him if he had ever heard of Pere Franois and the pirates.

"Nope, can't say I have."

Nancy and Julie Anne grinned. It was fun to have a story to match Clem's! Nancy told him Lightfoot's version of the hollow oak legend.

"Well now, ain't that somethin'?" he said, removing his battered straw hat and scratching his head. "Thought I knew all the stories about this neck o' the woods."

By this time they had reached the hollow oak with the arrow pointing south and went in that direction to look for another one. After a bouncy ride they came to a stream of rushing water filled with rocks, many of them sharp.

When Clem headed for it, Julie Anne cried out, "Oh, you're not going to try crossing this?"

"I sure am," Clem replied. "Been through here many times."

The girls held on tightly as the old, open car was driven into the water. It swung from side to side and slid off the rocks. Clem had a determined look on his face.

"This is crazy!" Julie Anne whispered.

Nancy thought so too, but before she had a chance to say this out loud, the car gave a sudden jerk. The right wheels landed up on the rocks. The car tilted precariously and went out of control.

The next instant it went over on its side, throwing the occupants into the rock stream!

CHAPTER VIII.

Exciting Plans

FOR a few moments after the car went over, there was no sound except that of the rushing water. Then Nancy, soaked from head to toe, arose and looked around. To her relief Julie Anne was pulling herself up. Both of them were concerned about Clem. But the next second he stood upright and gazed sheepishly at the girls.