publicity," Amy declared. "Perhaps you're right about hiding."

"I'd stay off the street if possible," Penny advised, arising to leave. "And it might be a good idea to take all your meals in."

"I shall," Amy promised. "Thank you for bringing me the warning. I appreciate it more than I can say."

"If there are any new developments I'll keep you posted," Penny said as they parted at the door. "The truth surely will come out within a few days."

She walked back to Pearl Street for her automobile, but did not drive home. Instead she turned toward the Gage Galleries.

"It seems to me the police and museum authorities have overlooked one important clue," she reflected. "I can't help thinking that the guard Susan and I met in the corridor may know something about the case. At least he should be questioned."

While it was true that a museum official had vouched for the honesty of the employee, Penny could not forget that the man had seemed greatly embarrassed at the encounter in the dark hall.

She was quite aware that the loss of the valuable painting really was none of her affair. Nor would she have taken such a personal interest in the case had it not been for her acquaintance with Amy Coulter. She felt that if the girl were to be cleared of suspicion, someone would have to work in her behalf.

Penny entered the Gage Galleries by the main front door and spoke to a guard whom she knew by sight.

"Have you heard anything new regarding the missing Rembrandt?"

"No, Miss," the man responded politely. "The theft of the painting was a severe loss to the museum. So far the police have made no progress in tracing the crook."

"Can you tell me where I can locate a man by the name of Hoges who is employed here?" Penny next inquired.

"You will not find him at the Galleries, Miss."

"You mean he's off duty for the day?" Penny asked in disappointment.

The guard's response came as a distinct blow.

"No, Miss. Mr. Hoges is away on a month's vacation. He left the city yesterday to travel in the South."

CHAPTER V

Behind the Panel

Penny was disheartened at the information. With the museum attendant out of the city, she could not hope to be of assistance to Amy Coulter. The situation looked very dark for the young sculptress unless other clues regarding the identity of the art thief were discovered soon.

"I wonder if this man Hoges really did go away on a vacation?" Penny mused. "He certainly vanished at the psychological moment!"

Giving no hint of what was in her mind, she politely thanked the guard for the information and returned home. After leaving her packages she called upon Susan to relate the adventures of the day.

"I think you were wise to tell Amy to hide," Susan approved. "We know her story is true, but it doesn't sound that way."

Penny was not certain that her father would take a similar viewpoint. She intended to tell him about Amy that evening and ask his advice regarding the situation, but directly after dinner Mr. Nichols isolated himself in his study, devoting himself to a new case upon which he was working.

In the morning at breakfast Penny did manage to bring up the subject, but Mr. Nichols listened inattentively as he sipped his coffee.

"I don't believe you heard a word I said," Penny complained finally.

"What was that? Oh, yes, I did. You were saying something about Amy Coulter."

"Never mind," Penny sighed. "I can tell your mind is a million miles away tracking down a wicked criminal."

"I hope the villain hasn't gone that far," Mr. Nichols chuckled. "Oh, by the way, you might tell Mrs. Gallup I'll not be home for dinner."

Penny regarded her father severely.

"Dad, have you forgotten what day this is."

"Tuesday the twentieth."

"This is the night of Mrs. Archibald Dillon's big reception."

The detective looked disconcerted. "I forgot all about it," he admitted. "How I hate those affairs unless I'm there on a salary watching for gem thieves! Mrs. Dillon is the worst social climber in Belton City."

"Just the same we accepted this invitation and we'll have to go," Penny said sternly.

"I can't make it. I have important work to do."

"But Dad——"

"You go alone, Penny, and do the honors for the family. Tell Mrs. Dillon that I came down with croup most unexpectedly. Tell her anything you like, only count me out."

"She'll never forgive you if you don't go. Can't you possibly make it?"

Mr. Nichols frowned in annoyance. "I suppose I might be able to drop around late in the evening. Possibly in time to take you home."

"That would be better than not attending at all."

"All right, we'll leave it that way then. I'll meet you about eleven o'clock tonight at Mrs. Dillon's."

The detective hastily kissed his daughter goodbye and hurried away to the office.

Penny did not look forward to the coming party. While Mrs. Dillon's receptions were always elaborate, usually they were boring. Susan had not been invited and she doubted that many young people would attend.

Penny sighed as she reflected that she might have spent a pleasant evening with a book. But she brightened a trifle as it occurred to her that the party would give her an opportunity to wear her new blue evening gown and silver slippers.

Eight o'clock found her en route to the Dillon residence in a taxi. The car swung into a curving drive and halted in front of an imposing, white colonial house. A liveried servant opened the automobile door for her and Penny joined several other guests who were entering the marble hallway.

"Miss Penelope Nichols," announced a servant.

It was all very formal and made Penny feel slightly ill at ease. She paused dutifully to greet her hostess.

Mrs. Archibald Dillon, a plump woman, well past middle age, was gowned in an elegant beaded dress, low-cut and far too conspicuous for the occasion. She had acquired wealth through marriage, but while she was active in many clubs and various types of charity work, she had never been able to achieve her social ambitions.

"My dear, didn't your father come with you?" she inquired, giving Penny's hand a slight pressure.

"No, Mrs. Dillon, he was detained at the office on an important case. However, he will surely drop in before the evening is over."