"About what?" George asked.

"That Joe Swenson works at the factory, all right."

"But they said n.o.body by that name was there," Bess objected.

Nancy smiled. "For reasons of his own, he could be using another name."

"Like what?" George spoke up.

"Dahl," Nancy answered.

"His mother's maiden name!" Bess declared. "Oh, Nancy, you're a genius!"

"Better not praise me until I've proved my hunch right," Nancy cautioned.

"Will you phone Mr. Weston and ask him?"

"No, Bess. I want to talk to Joe Swenson without his suspecting anything. If he's using an a.s.sumed name, it may be because he's hiding something. Suppose he finds out someone has been inquiring for him? He may run away."

"You're right," George agreed.

Reluctantly the girls rode back to River Heights. "See you tomorrow," Nancy told Bess and George as she stopped at their homes. Upon reaching the Drew house, she found Hannah Gruen awaiting her with a message.

"Ned Nickerson has phoned you five times, Nancy," Hannah said with a smile. "It seems that he wants to invite you to a dinner dance. One of his fraternity brothers is giving it-on the spur of the moment-tonight. Ned would like you to call. I have the number."

Nancy's heart was already pounding with excitement as she dialed. Of course she would accept!

"Great!" said Ned. "I was about to give up hope. Can you be ready in an hour?"

"I'll do my best," Nancy, replied.

Singing a gay tune, Nancy quickly disrobed, jumped under a shower, and was dressed in three-quarters of an hour.

"You look lovely, Nancy," Mrs. Gruen complimented her.

"Oh, thank you." Nancy surveyed herself in a long mirror. The pale-green chiffon dress was very becoming, and the gold evening shoes she wore set it off to advantage.

Still humming gaily, Nancy went downstairs holding her white wrap. Ned arrived in a few minutes and they drove off in his car. At first conversation was in a light vein, then Ned asked if Nancy had located the Raybolt arsonist yet.

"No. How about you?"

Ned replied, "All I know is what I read in the papers-first, that Mrs. Raybolt remains in a state bordering on collapse. She's firmly convinced her husband lost his life in the fire."

"The police and fire investigators don't think so," Nancy remarked.

"I do have one interesting piece of news. The police are busy working on a new angle. A clue, which they're withholding from the public, is expected to bring about the arrest of the criminal within a day or two."

"Is it possible that the police suspect Joe Swenson?" Nancy asked herself aloud. "If they arrest him, it will ruin all my plans for trying to help his family!"

"You're being very mysterious," Ned complained good-naturedly. "Why would the police suspect Mr. Swenson? How about letting me in on the secret?"

Nancy laughed. "Maybe you shouldn't beg too hard, Ned. You may find yourself being called upon to do all kinds of outlandish sleuthing jobs."

"I'm at your service," Ned replied quickly.

Little by little, Nancy told him the details. When she had finished, Ned said, "You've certainly done some terrific detective work! Well, good luck tomorrow. Wish I could be with you, but I'm slated to go on an all-day trip with my dad."

Nancy and Ned reached the home of his fraternity brother. Sounds of popular songs being sung in harmony by the guests drifted out. Laughingly, the couple hastened their steps.

All the boys and girls were strangers to Nancy, but she liked them at once. She found them intelligent and full of fun, and they quickly made her feel as if she had always been part of the group.

At the long dinner table the boy on her right, Phil Roberts, proved to be very entertaining. He told several amusing and true stories about strange letters which had come to the attention of the post office.

"Where did you hear about these letters?" Nancy asked him, after the laughter had subsided.

"Oh, my father's the Stanford postmaster," Phil explained. "He told me."

Immediately Nancy wondered if Phil could have heard anything to shed light on the reason why Mrs. Swenson was not receiving mail from her husband. It took Nancy nearly five minutes to formulate a diplomatic question.

Finally she said, "If someone's mail isn't being delivered, what could be the reason?"

Phil smiled. "Two that I can think of. First, no one is writing to the person, and second, his mail is being stolen." Suddenly he looked intently at Nancy. "What made you ask me that question?"

"Because I know someone who should be getting mail but isn't. If there were money or checks in the letters, a thief might steal them."

"A certain kind of thief would. Say, Nancy, I'm going to tell you something-it's kind of confidential-but I think it might help your friend."

Nancy listened intently for the secret she was about to hear.

CHAPTER XII.

Incriminating Evidence

"FOR several weeks," Phil began, "my father and a good many other postmasters have been receiving reports like the one you've just told me, Nancy. The police and the Postal Inspectors Division have been investigating but haven't caught anyone yet."

"Hm," said Nancy. "Then my friend could easily be one of the victims."

Just then a record of dance music began to play and Ned claimed Nancy. For the remainder of the evening there was no chance to resume the conversation about stolen letters. But throughout the evening, the matter was constantly on her mind. By the time the party was over and she had said good night to Ned, the young sleuth had a theory about the thefts. To start solving this mystery, she must first talk to Joe Swenson.

By ten the following morning Nancy was on her way, with Bess and George in the front seat of the car with her. In her purse was the diary. The cousins were intrigued when Nancy told them about the dinner dance.

"Lucky you!" said Bess, pretending to pout. "Couldn't Ned have found a couple of blind dates for George and me?"

Nancy laughed, then turning serious, said, "If we find Joe Swenson, I'm going to ask him point-blank if he has mailed any letters containing money to his wife."

She did not explain her reason for this, not wishing to betray Phil's confidence about the money, money orders, and checks being stolen from mail.