g
place in the attic, and that they were the fortunate instruments
selected by fate for the purpose of bringing the wrongdoers to justice.
It gave them a delightful sense of superiority over the other girls,
whose heads were full of nothing but tennis and croquet, and who never
troubled themselves with a thought about the missing treasure.

"Merle is the only one who knows anything," said Lindsay, "and I verily
believe 'The Griffin' must have bribed her."

Mrs. Wilson evidently used the utmost precaution in her visits to the
top landing. In spite of the pains they took to watch her movements, it
was some days before they found the propitious moment. "All things come
to those who wait," says the old proverb, however, and it proved true in
this case.

One afternoon, through the chink of the bathroom door, they saw her walk
into the gallery as if she were going to the upper story. As stealthily
as Indians they crept after her. They tiptoed along the passages, and
just caught a glimpse of the tail of her skirts as she passed up the
winding staircase and entered the lantern room. Very quietly they
followed on to the little landing, and listened for a moment outside the
closed door.

"What is she doing?" whispered Cicely.

"That's what I want to find out."

They both tried to peep through the keyhole, and bumped their heads
together in the attempt.

"I can hear her moving!"

There was a slight noise inside, almost like the clicking of a latch,
then all was perfectly silent.

Lindsay could bear it no longer.

"Here goes!" she cried boldly, and flung open the door. To her utter
amazement, the room was absolutely empty. Mrs. Wilson had vanished as
completely as if she had been a ghost.

CHAPTER VI

Monica

The two girls rushed into the empty room and examined every corner
minutely. There was not a trace of any secret exit to be found. The
opening through which Mrs. Wilson must have disappeared was evidently
marvellously well concealed.

"Where can she be? It's like magic!" whispered Cicely.

"Wherever she's gone, I suppose she'll have to come back," replied
Lindsay.

"Listen!" said Cicely, with a start.

It was the same strange sound again which they had heard on their former
expedition--a low, long-drawn-out moaning, as of someone in pain, feeble
at first, then growing louder, and suddenly ceasing.

"Oh! I wonder if she's hurting anybody?" cried Cicely, shuddering with
horror.

"I'd give a gr