Mackson gamely agreed to do as the rest did.
"I did hope I could go with you to-day," said Mr. Blackford, "but I have received a telegram that calls me away. I wonder if you could postpone it?"
"Of course!" exclaimed Betty. "There is no great hurry, and besides, I think we will all be the better for a rest. Is your business prospering, Mr. Blackford?"
"Yes, indeed, thanks to the way you girls helped me out by finding my five hundred dollar bill. But this is not business. I don't mind telling you that I am seeking for a long-lost relative—a sister—and I have engaged a firm of private detectives to look for her. They just sent me word that they are on the track of a person who may be the one I have been looking for so long. So, under the circumstances"
"Oh, of course, go by all means!" exclaimed Mollie. "We can meet you later, anywhere you say."
"Then suppose we meet here, say a week from to-day, and try for the ghost secret. By that time I may have found my sister, or have suffered another disappointment—and there have been many of late," and he sighed.
The week that followed was a busy one for the Outdoor Girls. Mollie had her car put in
