The three girls excused themselves and went outside. "Perhaps, Helen," Nancy said, "you'd like to stay at the inn. I'll be driving back, and can stop at your house to pick up whatever clothes you need."

"Thanks, Nancy. I'd like to stay. I'll phone Mother."

Emily asked if Nancy would have a chance to do her a favor in River Heights. "I'd ask Aunt Hazel, but she wants to get back here as soon as possible with my diamonds."

"I'll be glad to. What is it, Em?"

"Find out if the Empire Employment Agency has any waitresses available."

"Did you get Mary Mason through them?" Nancy asked.

"No. She stopped here. But her references were excellent, so I engaged her."

"I'll be happy to do the errand for you, Emily," Nancy said.

Mrs. Willoughby pulled up in her black sedan and Nancy climbed in front. John had come outside too.

"Don't forget," he said to her, "we have a skin-diving date when you get back."

At that moment Maud Potter hurried from the inn to the car. "I'll come along, if you don't mind," the social director said blithely.

She hopped in beside Nancy without waiting for an invitation. Mrs. Willoughby's lips tightened, but she made no comment. Good-bys were exchanged and the car started off.

Soon the sedan was speeding along the main highway. "Any ideas about your burglar?" Maud asked Nancy.

"No," Nancy admitted. "Except he might have been trying to break into Dad's safe."

Maud c.o.c.ked her head. "Does your father keep important papers at home?"

"Sometimes," Nancy replied noncommittally. She tried to hide her annoyance at the woman's inquisitiveness.

Mrs. Willoughby frowned disapprovingly. "Don't ask so many questions, Maud."

The social director shrugged. Once more she turned to Nancy. Arching her eyebrows coyly, she said, "I'd love to meet your dad sometime. I understand he is a widower."

"This is the last straw!" Nancy thought. Though annoyed, she had to suppress a smile at the woman's remark. Maud Potter certainly was not the type of person to interest her father!

"Dad keeps very busy, and travels a lot on his cases," Nancy said coolly. "He's away now."

Maud's coyness vanished. "I see. No time for social life," she said sarcastically.

To Nancy's relief, the woman spoke hardly at all for the balance of the trip. Presently Mrs. Willoughby pulled up into the winding driveway of the Drews' handsome brick home, surrounded by a velvety green lawn.

Nancy expressed her thanks for the ride and said good-by. She hurried into the house, for the moment forgetting Lilac Inn completely. Hannah Gruen greeted her with, "Oh, Nancy dear. I'm so glad you're back. I've been frantic!"

Nancy hugged the pleasant-faced woman, who said that Police Chief McGinnis had stopped at the house to investigate the burglary.

"No silver or other valuables are missing," Hannah went on. "But your room is a mess. Whoever was here must have been after something you keep there." The woman frowned worriedly.

Nancy dashed up the stairs. What a sight met her eyes as she entered her room! Bureau and chest drawers were open, their contents spilling out. Perfume bottles lay overturned on her dressing table. Clothes had been pulled from the closet and flung onto the bed and floor.

Mrs. Gruen, who had followed Nancy, explained, "Chief McGinnis wanted me to leave everything like this for you to see."

Nancy nodded. "How was the house entered?"

"Through the back door," Hannah replied. "The chief said the intruder must be an expert lock picker and burglar. He left no fingerprints."

Nancy hurried into her father's bedroom. Nothing here had been disturbed apparently. She went into the adjoining den and was relieved to see that the thief had not broken into the safe.

"The only thing missing from here is my picture," Nancy reported to Hannah.

"Oh, dear! What does it all mean?" the housekeeper asked worriedly.

Before Nancy could continue, the phone rang, and she answered it.

"Miss Nancy Drew?" a woman asked.

"Yes."

"This is Burk's Department Store. I'm Mrs. Reilly of the fine jewelry department. I made a terrible mistake when I sold you that watch this morning. The price was one hundred and twenty-five dollars, not fifty as I told you. Do you still want to keep it?"

Utterly astounded, Nancy said, "Mrs. Reilly, I didn't buy a watch this morning! I was out of town."

"Isn't your charge account number 10-4875?"

"Wait, please. I'll check."

Nancy hurried to open the desk drawer where she had put Burk's charge plate. Its leather case was there, but the metal plate was not inside. "It has been stolen!" Nancy exclaimed.

With a sense of foreboding, she returned to the phone. "I'll drive right down to see the manager," Nancy said. "My charge plate has been stolen, I'm afraid."

Nancy paused long enough to tell Hannah of her discovery, and to notify Chief McGinnis. The officer said he would meet her at the store manager's office.

Just as she was about to enter Burk's, Nancy stopped short. To her amazement, she saw Maud Potter entering the Empire Employment Agency office across the street.

"Now what's up?" Nancy wondered. "Is Maud trying to engage a waitress for the inn, too?"

Puzzled, she hurried into the department store and took an elevator to the third-floor office of the manager, Mr. Goldsmith.

"I'm Nancy Drew," she greeted him pleasantly. "I want to explain-"

She got no further. With a stern look, the manager said curtly, "I know all about the watch you claim not to have bought early this morning. But how about those other items you carried away?"

Dumfounded, Nancy could only echo, "Other items?"

Grimly the manager continued, "I don't know what your game is, Miss Drew. But unless you have a twin, you owe Burk's Department Store for merchandise worth two thousand dollars!"

CHAPTER IV.

Address Unknown NANCY felt she must be dreaming. Not only had the thief charged two thousand dollars to her account, but the store manager seemed to believe that Nancy herself had made the purchases.

"I must have a double!" she thought. "Doris Drake's friend Phyl was right in thinking she was talking to me. Someone is impersonating me! It's possible this person or a friend of hers broke into our house, took the charge plate, and some of my clothes for her to wear!"

Outwardly, Nancy tried to appear calm. "I couldn't have bought those things, Mr. Goldsmith," she insisted. "This is the first time today I've been in Burk's."

For answer, the manager pressed a buzzer. Three women entered. He introduced them as Mrs. Reilly, Miss Coogan, and Mrs. Watson, "Mrs. Reilly sold you the watch," said Mr. Goldsmith. "From Miss Coogan you bought an expensive mink stole. Next, you purchased two high-priced dresses in Mrs. Watson's department. Ladies, do you identify this girl?"

The saleswomen nodded. Each one identified her as Nancy Drew, the young woman she had waited on, and who had signed sales slips for each purchase.

"This is preposterous!" Nancy cried, her blue eyes flashing. "Someone is impersonating me. She stole my charge plate. I want to see those sales slips."

Just then, to Nancy's relief, Chief McGinnis entered the office. He and the Drews were old friends, and he greeted Nancy cordially.

Mr. Goldsmith spoke up. "Glad you're here, Chief. I was just going to call you." He explained what had happened.

The police officer replied calmly, "If Nancy Drew says she didn't buy anything, she didn't. Let's get down to facts, Mr. Goldsmith. I'm here to help Miss Drew, and Burk's also."

The chief quizzed the salesclerks briefly. After hearing their stories, he said gravely, "Nancy, I'm afraid this young woman who resembles you so closely-and forged your signature on the sales slips-may continue to take advantage of it."

Nancy smiled ruefully. "I realize that." She was more convinced of this than ever when the sales slips were brought to the office. The forgery was excellent. Nancy's impersonator must have carefully practiced the signature on the charge plate.

Mr. Goldsmith sighed wearily. "I'm sorry, Miss Drew, about this whole matter, and that I suspected you of dishonesty."

"That's all right," she replied. "The main thing is to track down the culprit and get back your stolen property."

She asked the clerks what her "twin" had been wearing. "It was a lovely light-blue dress," replied Mrs. Reilly. "Printed silk, with white flowers."

Nancy gasped. "I have a dress like that. And I don't remember seeing it in my closet today."

"The woman no doubt took it," the police chief said, frowning. "Nancy, be very careful. This impersonation may mean not only annoyance, but possible danger for you."

Mr. Goldsmith promised that Burk's private detective and all the store's sales personnel would be on the lookout for Nancy's unknown double.

As the young sleuth left the store with Chief McGinnis, she said to him, "I wonder if this person actually is my double or is only cleverly made up to resemble me."

The officer frowned. "If it's the latter, the thief will be harder to catch. She may not pose as Nancy Drew again for some time. But I'll have my men start working on the case from every possible angle." He admitted that no clues to the thief at the Drew home had been found. "I'll post a twenty-four-hour guard at your home."

"Good," Nancy said. "Hannah will feel much better, since I have to return to Lilac Inn this afternoon, and Dad's away."

Nancy said good-by to the chief and hurried across the street to the employment agency. She wondered if by chance Maud Potter might still be there. But when Nancy entered the office, the only person there was the woman manager, seated at a desk.

"Can I help you?" she asked Nancy.

"I'm here at the request of the new owners of Lilac Inn," Nancy replied. "Has anyone else been in to ask about a waitress to work out there?"

"No."

As Nancy asked her next question, she was thinking, "Why was Maud in here?" Aloud she said, "Have you any waitresses on your list?"

"Not at present. We'll call you if any apply."

On impulse, Nancy asked her, "Could you tell me if you've ever had a Miss Mary Mason on your waitress list?"

The woman opened a nearby file and flipped through a folder. "No, we haven't."

Nancy thanked the manager and left the agency. When she arrived home and told Hannah the latest developments, the housekeeper was more upset than ever.

"I feet in my bones that this impersonator is up to something sinister," she declared. "I wish your dad were home."

"You'll be safe here, Hannah," Nancy said a.s.suringly, and told Mrs. Gruen that a policeman would be a.s.signed to guard the house. "And speaking of Dad, I'm going to call him right now and ask him if he took that picture of me with him."

"While you do that, I'll fix some lunch for us," Mrs. Gruen offered. "You must be starved. It's two o'clock."

Nancy went to the hall telephone and a minute later was requesting the switchboard operator at the Cleveland hotel to ring Mr. Drew's room.

"h.e.l.lo?" came the lawyer's deep, resonant voice.

"Hi, Dad! How good to hear you!" Nancy said happily.

She gave him an account of the burglary and succeeding events. Carson Drew was greatly concerned. "Nancy," he added in a troubled voice, "I didn't bring your photograph with me. Your double must have taken it. She has already fooled four persons who don't know you well. With the help of the picture, she may try something bolder," he stated.

"You think this girl has some ulterior motive. other than faking my charge account, don't you, Dad?"

"I'm afraid so. Be on your guard, Nancy. Try to stay with a group as much as possible, particularly after you return to Lilac Inn."

The lawyer added that he would be home the next day. "I'll look into the whole affair then."

Nancy promised to be careful and said good-by. She and Hannah sat down and ate lunch. Finally Nancy said she had to pack and leave.

"But first I'm going to try locating that waitress Mary Mason." Nancy picked up the telephone directory and thumbed through it until she reached the M's. She called two families named Mason, but each denied having a relative Mary.

"Probably," Nancy surmised, "Mary did not live in this area."

Deep in thought she went upstairs and took a suitcase from her closet. Nancy quickly placed additional garments in it, then gathered up her skin-diving equipment: green rubber fins, a diving mask, and an aqualung. Finally, Nancy packed a rubber suit which would insulate her body against the cold river water, and an underwater camera her father had given her.

Nancy kissed Hannah good-by and got into her convertible. She drove to the Comings' home and picked up Helen's suitcase, then set out for Lilac Inn.

Her thoughts revolved around the mystery out there and also on the problem of her impersonator. "No one could look enough like me to be absolutely identical. Why, even identical twins have distinguishing characteristics," she told herself with a smile, "such as the shape of fingernails, voice tones, and facial expressions."

The late-afternoon traffic on the highway to Benton was becoming heavy. Nancy turned from the main road onto a very narrow, less-used one. Presently, in her mirror, she saw a red panel truck behind her coming along at an alarming speed. Nancy, at the same time, noted an arrow indicating a sharp curve ahead. She braked and motioned the truck driver to slow down.

Either he did not see her signal, or was ignoring it. Instead of slowing down, the truck's speed increased, as if to pa.s.s her. The curve was not wide enough for two cars to go side by side. On Nancy's right was a deep ditch, filled with water.