However, the following day found her again at her station in the post office. The task of waiting and watching seemed even more tiresome than before. When she came home late in the afternoon Mrs. Gallup offered scant sympathy.

"I never heard of such a silly thing," she declared. "Standing all day in the post office! I don't know why your father permits you to play around at being a detective!"

"If you think it's play just try standing in one spot for eight hours!"

Penny said indignantly.

"I'd have better sense," Mrs. Gallup retorted. Then she softened. "I know you're tired, Penny. Sit down and rest while I make you a cup of hot chocolate."

With a blissful sigh, Penny sank into an upholstered chair. She was looking at a magazine when the housekeeper returned with a pot of chocolate.

"Here is a letter for you," she mentioned, dropping it into the girl's lap. "It came this afternoon."

Noticing that it was postmarked Belton City, Penny quickly tore it open. The envelope contained a brief note from Amy Coulter, who had written to give her new address.

For a long time after she had finished reading the message, Penny sat staring down at it without being aware of her preoccupation.

"I hope it isn't bad news," Mrs. Gallup said anxiously.

"Oh, no." Penny folded the message and thrust it into her pocket. "I was only thinking."

Her thoughts had not been pleasant. She still liked Amy Coulter despite the girl's strange actions, yet she felt that she could not continue to help her without positive proof of her innocence. If only Amy had explained her connection with George Hoges!

"You haven't been a bit like your usual self, Penny," Mrs. Gallup said severely. "You're not sick, are you?"

"Of course not. I'm just tired."

"You've had too much excitement lately. It seems to me this household is always in turmoil. The past week all I've heard of is robberies, prowlers and more robberies!"

"At least we've had no murder yet," Penny chuckled. "By the way, what did Dad say last night when you told him about the man we saw hiding behind the garage?"

"He thought probably it was some crank. But I noticed he examined the ground for footprints."

"Perhaps the prowler was the same person who broke into Dad's office,"

Penny remarked. "Only that doesn't seem reasonable either, for what could anyone be after here at the house?"

"Silverware or possibly some of your father's papers."

"He doesn't keep anything of great value here as far as I know."

Before Mrs. Gallup could make a response the telephone rang and she went to answer it.

"Can you come, Penny?" she called a moment later. "It's for you."

The girl hurried to the adjoining room and was surprised as she took the receiver to hear Mrs. Dillon's voice. The woman was greatly agitated.

"Miss Nichols, you were right about the picture," she began abruptly.

"I communicated with the museum authorities as I promised and they told me that the painting is a fake!"

"I thought it would turn out that way," Penny commented in satisfaction.

"I can't understand how I was duped," Mrs. Dillon went on excitedly.

"I was so careful. I've been cheated out of four thousand dollars."

"Four thousand!" Penny exclaimed. "Why yesterday you told me you had paid only half that sum."

"Since then I've made the final payment."

"But I warned you, Mrs. Dillon," Penny cried in exasperation. "Why did you do it?"

"Because I couldn't help myself," the woman wailed. "My friend--the agent convinced me that if I didn't complete the payments I would get into serious trouble with the police--that we both would be disgraced."

"And you believed his story! He only cheated you!"

"No, he wouldn't do that," Mrs. Dillon replied firmly. "This gentleman's reputation is above reproach. He couldn't have known any more than I did that the Rembrandt was a fake."

"The only thing for you to do now is to reveal everything," Penny urged. "Tell me the name of this man."

"No, I can't. I have promised to keep silent."

"Mrs. Dillon, I am unable to understand your att.i.tude. Don't you want to help capture the persons who tricked you?"

"Yes, I'll do anything I can except reveal this gentleman's ident.i.ty.

I'll learn from him the name of the firm where the picture was bought and notify the police."

Penny made a grimace which Mrs. Dillon could not see. After a moment's silence, she asked bluntly:

"Is it Hanley Cron whom you are protecting?"

"Certainly not," Mrs. Dillon retorted, and hung up the receiver.

"I wonder if she told the truth?" Penny thought, turning from the telephone. "At least she was afraid to answer any more questions."

It occurred to the girl that if Hanley Cron were not the mysterious agent who had visited Mrs. Dillon the previous afternoon, then the caller must have been the elderly gentleman with the black leather brief case. Recalling that she still had the license number of the man's car, Penny thought that it might be well to show it to her father and ask him to trace the owner for her. Mr. Nichols would soon be coming home for it was nearly dinner time.

Penny searched in her purse but the notebook was not there.

"Mrs. Gallup, have you seen a little green paper-covered book anywhere in the house?" she inquired anxiously.

"I saw it in your room this morning," the housekeeper informed. "I think it was on the dresser."

"Oh, yes, I remember now, that was where I left it!" Penny laughed in relief.

She raced up the stairs two at a time, forgetting that she had ever been tired. To her delight the little book was lying just where she had dropped it.

She caught it up, rereading the notations which she had made the previous day. Hearing her father's car on the driveway, she slipped the notebook into her pocket and turned to leave. As she crossed to the door, her eye chanced to rove toward the desk. She stared in blank amazement.

The Black Imp was gone.