Nancy said it indicated one thing to her. "There is something bigger involved. My heirloom may be only an incidental aspect. I believe that whatever is going on actually has nothing to do with Douglas House.

"This may be a wild theory on my part, but I believe now that the same men who are stealing sheep took my brooch. They feared that if I were able to track them down, I would also uncover clues to their racket."

Fiona looked at the young sleuth admiringly. "I can see why you are an internationally known girl detective."

Bess was thoughtful. "In other words, Paul Petrie from River Heights, the mysterious Mr. Dewar, and the red-bearded man are in the sheep racket together!" Nancy nodded.

George had another thought. "Nancy, you suspected the men who moved out of that houseboat. Do you suppose the stolen brooch might have been there?"

"Maybe," said Bess, "but you couldn't hide a whole flock of sheep!" The girls laughed.

Nancy was not ready to stop talking about the mystery. "Since we suspect smuggling, wool and hides could have been hidden in the houseboat until it was time for shipment, maybe to the United States. That's where Paul Petrie might come into the picture."

"That's right!" said Fiona. "If the authorities are looking for missing live sheep, perhaps they wouldn't be looking for wool or hides."

The four girls walked along in silence for fully a minute. Then Nancy said, "Tomorrow let's take a ride to that road where I heard the bleating inside the truck."

"You mean go back to the area near Mrs. Drummond's croft?" Bess asked.

Nancy nodded and turned to Fiona. "Where could that truck have been coming from? If we go in that direction, we might pick up a clue."

Fiona said that the truck would be coming from the glen at the foot of Ben Nevis. Her face brightened in antic.i.p.ation. "I have an idea. Why don't we camp out overnight? The glen is a lovely spot, popular with many mountain climbers. They even have running races up and down Ben Nevis."

George was intrigued. "How high is the mountain?"

"About forty-four hundred feet."

Bess looked aghast. "You say they run up?"

"That's right."

George grinned. "I want to see that place, mystery or no mystery!"

The American girls were thrilled by the idea of camping out, and later Nancy asked Lady Douglas about equipment they could use. After dinner, Nancy's great-grandmother took the girls on a tour of the mansion.

"We'll end our trip in the attic," she added, "and you girls can look there for proper hiking and camping clothes."

As the tour went on, Bess thought she had never seen such an a.s.sortment of armor and so many oil portraits in one place. There was even a knight's armor standing in a corner!

The attic was not in the least what Nancy had expected. It was very large and handsomely finished. Lady Douglas said it had once been a game room, where the men of Douglas House and their guests played billiards. Now there was the usual collection of old furniture, books, and trunks.

"You will find all sorts of clothes and blankets in the trunks," said Nancy's great-grandmother. "Help yourself to anything appropriate you can find."

The visitors were intrigued by the contents of the trunks. There were many kilt skirts, white blouses, long black socks, and various kinds of caps worn by Scottish girls.

Nancy had a sudden idea. "These would make good disguises," she said, then stopped speaking, not wishing to worry Lady Douglas with what was going through her mind. But the other girls immediately got her message.

"Let's try some on!" George urged.

To Nancy's surprise, the tartan outfits belonged to several clans, and she asked her great-grandmother about this. The elderly woman smiled. "Various relatives in our family came from different clans and brought these costumes with them."

After trying on a few combinations, Fiona chose the Ogilvy tartan of small red-and-pale-blue checks with lines of white. George's black hair was set off by the yellow-and-black plaid of the McLeods of Lewis.

Bess looked very pretty in the Stewart dress, a combination of large white squares interspersed with stripes of pale green and red.

"Nancy, I'm glad that you chose the Cameron tartan of my mother," said Lady Douglas. "It is very becoming." Nancy did look attractive in the flashy tartan of large bright-red squares edged with stripes of dark green.

"You're sure you don't mind our borrowing these?" she asked her great-grandmother. "They may become soiled or torn on our camping trip."

Lady Douglas a.s.sured her that the costumes were not valuable and had been worn many, many times before. "I am sorry that I do not have sleeping bags or bedrolls, but in one of these trunks you will find knapsacks and warm blankets."

After the necessary equipment had been collected, the group went downstairs. Morag was told about the trip, and by the time the girls were ready to leave the following morning she had packed enough food for three good meals.

Morag admired the girls as they started off. "Aye, and ye be lookin' like bonnie Highland la.s.sies for sure!"

The girls smilingly thanked her and said good-by. Fiona directed Nancy to drive by a shortcut to the road which went past Mrs. Drummond's croft and on to Ben Nevis. The foursome looked for any possible clues to the sheep rustlers-an encampment, or a place where a truck might have pulled off the road. They found nothing of significance.

When the girls reached the glen, they crossed a bridge over a waterfall that cascaded from a rushing, boulder-filled mountain stream.

"This scenery is gorgeous!" Bess exclaimed.

On either side mountains rose sharply but not too steeply for climbing. Rocks were interspersed with trees and bushes. Here and there grew patches of heather, its colorful purple tint giving the slope a friendly look.

The road ran alongside the water. Here and there were protected areas that Fiona said were for campers. Presently they met a group of hikers, who were about to start a race up Ben Nevis.

Nancy pulled to the side of the road and the girls got out to watch. There were four boys dressed in white trunks and jerseys with their school insigne. One boy, seeing Fiona, hailed her.

"Wish me luck!" he called. "We will run to the big pine tree. The fastest time up and back is twenty minutes."

She nodded and told the girls he was distantly related to her. The Americans were amazed at the agility and swiftness of the boys as they literally ran up the mountainside. As they neared the tree, Fiona said, "Aye, that is good. My cousin Ian is ahead!"

Ian was the first to start down the slope. This feat seemed far more dangerous than going up. By now all four girls were looking at their wrist-watches. Fiona exclaimed, "I think my cousin will equal the record!"

Ian did. His time was exactly twenty minutes, while his companions were clocked at twenty-five, twenty-eight, and thirty minutes.

The Scottish girl introduced her cousin and the other boys, who immediately invited Fiona and her friends to join a group of campers up the river.

"Fiona, you know several of the girls," said Ian.

The offer was readily accepted and soon Nancy, Bess, and George were meeting Fiona's other attractive Scottish friends, most of them wearing kilts. Some campers were from the Isle of Skye and others from the town of Inverness. The Americans were made to feel at home at once.

There was a lot of chatter and laughter among the young people while they unpacked food kits. Soon everyone was eating luncheon.

Above the hum of conversation Nancy became aware of distant music. Suddenly she sat bolt upright. A few bars were being played over and over on a bagpipe, apparently somewhere far up on the mountain. The melody was Scots, WhaHae!

Nancy strained her eyes to see the player, but no one was in sight. Was he just over a ridge? The young detective began to recall various incidents and finally a startling thought entered her mind. Was that particular tune, by any chance, played whenever she was around? "And could it possibly be piped by Mr. Dewar to let his partners know I'm in the area?" Nancy mused.

Her three friends had not noticed the bagpipe music, which ended abruptly. She quickly told them about it. "I'd like to climb the mountain and look for clues to that mysterious piper!"