d Amy and Grace gave rather halting
assents. Mrs. 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 perfect order, and they toured over many miles of
splendid country. They had minor happenings and adventures, but nothing
of moment, if we except a few punctures and a blowout. Oh, yes, they did
run over a dog, breaking the creature's leg. But it was the dog's fault,
and Mollie steered out of the way so quickly that she nearly sent the
auto into a tree.

At the appointed time Mr. Blackford was at the hotel.

"Well, are you ready to go ghost-hunting?" he asked.

"We are!" cried Mollie, and once more they set off for the "haunted
mansion," determined to discover its secret if at all possible.

"I wonder what we'll find?" said Betty, as the car raced on.

CHAPTER XXI

THE MISSING GIRL

"Who would ever think we could be frightened here?" asked Mollie.

"Yes, it's quiet enough now," replied Betty. "Not a sign of a ghost."

"Nor flashes of blue fire," added Grace.

"Nor hollow groans," remarked Amy.

The Outdoor Girls, with Mrs. Mackson and Mr. Blackford, had reached the
so-called "haunted mansion." The day was a sunny one, perhaps that added
to the lack of nervous fears they felt as they stopped the auto, and
entered the place. This time they had gone to the mansion proper, having
driven through what