“Four—including my own!”

“And were there any transients here at that time?”

“Just one. A chorus girl named Mary Green. She stayed a couple of days and then said her show was closing up.”

The young detective wrote all these facts into her notebook and asked whether that was all.

“Not quite,” replied Mrs. Hilliard. “Last Friday Miss Violet Granger had a valuable oil painting stolen from her room, and a purse containing fifty dollars.... So you see the situation has become pretty serious. Two of our regular guests have moved away because of it, and others have threatened to do so if anything else is stolen.”

She looked doubtfully at Mary Louise. “I’m sure I don’t know how you would go about an investigation like this,” she said. “But perhaps you do. Are you willing to try it?”

“Of course I am!” cried the girl eagerly. “It’s just the kind of thing I love. I’ve put down everything you said, Mrs. Hilliard, and I’m all ready to go to work now. I want to see the hotel and meet the guests as soon as possible.”

“I think Mary Louise had better keep secret the fact that she is spying on them,” put in Mr. Gay. “Just let them think that she is a young friend of yours, Mrs. Hilliard, visiting you for her Christmas vacation. As a matter of fact, she wants to look up a young girl from Riverside, whose whereabouts have been lost by her relations. But use your own discretion, Mrs. Hilliard.”

“I will, Mr. Gay,” agreed the woman. “And I will take good care of Mary Louise for you,” she added.

“That’s right. No late hours—or being out alone at night, Mary Lou. Don’t forget that this is a big city, and girls can easily get lost.”