Mr. Drew chuckled. "I thought I'd surprise you, Nancy, but I didn't expect to scare that waitress."

"So many upsetting things have happened here, Dad," Nancy said, "I guess everyone's a bit nervous."

Mr. Drew said that until he had met the officer in the parking lot, he had heard nothing of the trouble at Lilac Inn.

"The lieutenant mentioned last night's explosion and fire here. Then he asked if I were the father of the Nancy Drew who had the accident on the side road to Benton."

"You haven't talked to Hannah?" Nancy asked.

"No. I came directly here." Mr. Drew put an arm around his daughter. "I'm concerned about you.

"I'm all right, Dad," Nancy insisted. "Really I am. By the way, have you talked to Chief McGinnis?"

"Yes. That's another reason I came here," her father said. "I had to phone him on a legal matter. He told me that you found the charge plate and the envelope with your name on it. By the way, there were no helpful prints on either the plate or the envelope."

Nancy decided to wait before telling her father of the other mysterious incidents, and now suggested that the men come into the dining room to breakfast. She made the necessary introductions. The Willoughbys and Mr. Drew were well acquainted and exchanged warm greetings.

Maud fluttered her eyelashes. "So you're the famous criminal lawyer," she said coyly.

Carson Drew did not like flattery, but nodded politely. He congratulated Emily on her forthcoming marriage. When the men had finished eating, Nancy and her friends went with them to see the burned cottage.

Emily told Lieutenant Brice everything that had happened but excluded the diamond theft. He rubbed his chin thoughtfully, then said, "All could be malicious pranks, not connected with the explosion. On the other hand, they could very well be part of some big scheme."

When the group reached the site of the burned cottage, they found John there. Nancy introduced him to her father and the police officer.

After Lieutenant Brice had probed the ruins of the cottage, Nancy and her friends gave him and Mr. Drew a full account of the previous night's events. When he heard of Helen's experience, Mr. Drew looked grave and suggested she return home.

Helen shook her head. "I can't desert Nancy."

The young sleuth smiled gratefully. Secretly she longed to tell her father the rest of the story-the trip to Benton, the diamond turning up in her purse, the faked message from John, and her skin-diving adventure. But all these, Nancy realized, were related to Emily's stolen gems.

Finally Lieutenant Brice announced, "I've found fragments of what I am positive was a time bomb you heard ticking, Miss Drew. I'll send an explosives expert over to verify this, however."

Carson Drew turned to his daughter. "Nancy, I wish I could stay here and help you work out this mystery. Unfortunately, I have to return to River Heights and review highly important evidence for a case I'm to try next week. But keep me posted."

"I will, Dad. In fact, I may see you if I do some sleuthing near home, as I plan."

Before leaving, Mr. Drew asked if Nancy had come upon any leads to her impersonator.

"Nothing definite, Dad," was all Nancy could in truth reply.

The attorney then advised Emily to engage a guard to stand night duty. "I can recommend an excellent man," he said. "His name is Carl Bard."

Emily agreed and Mr. Drew went inside the inn to telephone him. He returned shortly and said Mr. Bard would report there later.

"Fine," said Lieutenant Brice. "And I'll have a squad car patrol the inn frequently. I suggest that no one venture out alone-especially at night-until this case is broken."

Good-bys were exchanged, and Nancy stood waving to her father as he drove off. Meanwhile, Helen and Emily had started for the patio.

As Nancy hurried after them, she came to the tool shed. John had investigated it, but Nancy wondered if she might find some clue he had overlooked.

The door was open. She went inside. Spades, hoes, rakes, and other similar equipment lined the walls. Nancy studied the array. "Just ordinary garden tools," she mused. Then suddenly she noticed a pad of notepaper lying on a bench. Nancy picked it up and turned the pages, which contained various notations for the gardeners. One item, on the third page and in a different kind of printing from the other instructions, read: "Prune blue pipes near grove."

" 'Blue pipes,' " thought Nancy, as she tore out the sheet. "Now what does that mean? Could it possibly be a code message? Or a signal? I'll ask the gardeners."

She left the shed, and began to look for the men. The only man in sight was Gil, who was cutting the lawn with a power mower. She went up, and attracting his attention, asked him, "Can you tell me what 'blue pipes' are?"

"Never heard of 'em," Gil replied laconically.

"One more question," Nancy said. "Would you have any idea who used one of the inn's canoes yesterday afternoon?"

For a moment Gil's eyes narrowed. Then he brusquely replied No; he had not been near the dock all day. "Mr. John asked me the same thing. Well, I got work to do," he muttered, and quickly resumed his mowing.

Nancy walked meditatively toward the inn. "If Gil doesn't know what 'blue pipes' are, that message might well be a code phrase."

It occurred to her that perhaps Mr. Daly would be able to explain the term. Nancy went inside and found the elderly gentleman in his office, going over receipts. He looked up as she knocked and entered.

"Good morning, Nancy. Sorry I missed meeting your father."

Mr. Daly admitted that he had been wearied by his all-night vigil, and had gone to his room to rest. Nancy smiled understandingly and told him briefly of Lieutenant Brice's investigation.

Mr. Daly looked grave. "If all this danger continues, I'm going to insist that Emily and d.i.c.k sell the inn. A nice young couple shouldn't start marriage under such circ.u.mstances."

"I agree. But the person responsible for the trouble here must be caught."

"You're right, Nancy," Mr. Daly said, "I mustn't lose hope so easily."

The young sleuth then asked, "Mr. Daly, can you tell me what 'blue pipes' are?"

Mr. Daly chuckled. "Of course-my favorite subject matter is 'blue pipes'-or lilacs."

"You mean that 'blue pipes' are lilacs?" Nancy inquired with interest.

"Yes. The ancient name of the lilac was Blue Pipe Tree, a reminder of the time when pipes were made of its wood. See here."

Mr. Daly reached into a drawer of his desk and handed Nancy a half-finished tobacco pipe. "Carving is my hobby. I'm making this pipe from the wood of a fallen tree limb right here at Lilac Inn."

"Why, it's beautiful!" Nancy held up the pipe, admiring the delicate stem.

At that moment Jean Holmes pa.s.sed the office. She paused and looked in. Nancy greeted her, but the waitress barely answered. Her eyes were riveted on the pipe in Nancy's hand.

"Isn't this a handsome piece, Jean?" Nancy said pleasantly. "Mr. Daly made it."

"Oh, very." Jean nodded and hastened on into the dining room.

To Nancy it seemed that the waitress had acted almost frightened. Why?

Mr. Daly seemed not to have noticed. He went on to tell Nancy some interesting facts about lilacs. The old-fashioned, lavender-colored blossom and its white companion, so well known in America, originally came from Bulgaria, Hungary, and Rumania. But the double lilacs of pink, red, and purple, like those in the grove, were developed by horticulturists.

"The French developed the Lucie Baltet variety-the same as the stolen tree," Mr. Daly said sadly. "Many beautiful lilacs are named after famous French people, such as Joan of Arc."

"You're certainly an expert on every aspect of lilacs," Nancy complimented him as Mr. Daly paused.

Modestly, Mr. Daly admitted he had studied the subject intensively. He himself had planted most of the lilacs at the inn.

"They are considered a flower of mysterious power in the West Indies," he said solemnly. "Some people there believe that the perfume keeps away ghosts and evil spirits. A lilac tree is often planted near the front door so its branches can act as protection against evil spirits entering the house."

Nancy now pulled the sheet with the blue pipe notation from her pocket and pa.s.sed it to Mr. Daly. "Do you know anything about this?" she asked.

He glanced at it and said, "No. And I write out all the instructions for the gardeners. I never use the term 'blue pipes.' They wouldn't know what it meant."

"Have you any idea who might have written this?" Nancy asked.

"None whatever. And I can't figure out what it means. Besides, it's not time to prune lilacs. Have you a theory?"

"I'm not sure, except I have a hunch it's connected with the strange happenings at Lilac Inn and is a code message. I hope I can figure it out."

Nancy pocketed the sheet and left the office. Deep in thought, she almost b.u.mped into Emily.

"Oh, where's Detective Drew headed?"

The young sleuth laughed, then showed Emily the sheet. "Do you know who printed this strange notation?"

Emily stared at the message for several seconds. Finally she said, "No, but the printing looks familiar."

"Think hard and don't keep any secrets," Nancy urged. "This may be the turning point in solving the mystery!"

Staring into s.p.a.ce, Emily sought desperately for an answer. Suddenly she snapped her fingers. "I have it! That waitress who left here so suddenly! She used to print all the orders she took. I mean Mary Mason!"

CHAPTER XI.

A Tip from a Waitress "MARY MASON again!" exclaimed Nancy. "That settles it! I'm going to River Heights at once and talk to Mrs. Ernest Stonewell, the woman for whom she used to work."

Nancy decided to tell Helen her plan, so the two girls went out to the patio where she was reading. Nancy revealed her latest findings and told of her proposed trip. "Want to come?" she asked Helen.

"No, thanks." Helen chuckled. "You work better alone. What a clue this is! Maybe you'll come back with the mystery solved!"

"Don't count on that." Nancy smiled. "Where is everybody?"

"John's at the burned cottage with the explosives expert. Mrs. Willoughby and Maud are upstairs."

Nancy leaned toward Emily and said in a low voice, "I hope you won't mind my asking, but- but does Maud Potter have anything to do with your not reporting the diamond theft?"

Emily sighed. "Well, yes. You've probably sensed, Nancy, that she seems to have some influence over Aunt Hazel."

Helen's eyes grew wide. "You mean Maud's sort of-blackmailing her?"

The bride-to-be looked unhappy. "I'm really not sure."

"And," Nancy conjectured, "you're afraid Maud has some knowledge of the diamonds that may involve your aunt if the theft is publicized?"

"That's the feeling I have."

Before the girls could discuss the matter further, Maud herself came onto the patio. She sank into a chair. "Having a conference?" she asked sweetly.

"Yes," Emily replied promptly. "Nancy's going on a sleuthing trip to River Heights."

"Oh?" Maud's eyelids flickered. "You have what they call a 'hot clue'?" she asked Nancy.

"I hope so," replied the young sleuth calmly.

"Well, give my regards to your dad if you see him," Maud said airily.

Nancy rose. "I'd better get started. I'll pick up more clothes for you and me, Helen." She laughed. "Then we can return yours, Em."

Suddenly the group became aware that Jean Holmes, dressed in street clothes, stood in the doorway. She smiled timidly and said: "Miss Drew, I heard you say that you're going to River Heights. I need a few things I left in the room I shared in town with a girl friend." She turned to Emily, and asked permission to accompany Nancy and get them.

"All right," Emily said. "I trust you'll return in time to serve supper?"

"Oh, yes, Miss Willoughby. I'll take the afternoon bus back."

Nancy told Emily she herself probably would be back by evening.

"We'll be on pins and needles until then," Helen said.

Just before Nancy and Jean reached the convertible, Emily caught up to them. Drawing Nancy aside, she whispered, "I've been thinking -will you tell your father about my diamonds and the other incidents? Perhaps he can give you helpful advice. But please ask him to say nothing to the police, unless there's no other way out."

Nancy was delighted. She would feel much better if she could discuss this aspect of the case with her father.

In a few minutes she and Jean were headed for River Heights. Although Nancy had lost her handbag with wallet and driver's license in the fire, Mr. Drew had obtained special permission for her to drive until her new license was mailed. Fortunately, he had had a key to her car in his key case, and had left it with her.

"This is a lovely convertible," Jean spoke up.

Nancy smiled as the car rode smoothly past farm land and woods. "Where did you work before coming to Lilac Inn, Jean?" she asked.

"Many different places," the girl replied. "Florida in the winter, sometimes, and in the summer, I come north."

Later, as they neared River Heights, the waitress said abruptly: "Miss Drew, I had another reason for asking to ride with you. I wanted to tell you someone at the inn is trying to make trouble for you!"

"What do you mean?" Nancy asked, as they reached the outskirts of River Heights.

Jean hesitated at first, then said she didn't want to be accused of spying. "I think," she said finally, "Mrs. Potter is up to something funny!"