away, probably through dampness,--and the mice seem to
have eaten it too. And here's the keyhole! Isn't it _lucky_ we just
happened to take the books out that were in front of it!"

"But what are we going to do about it?" questioned Cynthia.

"_Do?_ Why, there's just one thing to do, and that is move the shelves
out somehow,--they seem to be movable, just resting on those
end-supports,--and get at that door!"

"But suppose it's locked?"

"We'll have to take a chance on that! Come on! We can't move these books
and shelves away fast enough to suit me!"

They fell to work with a zest the like of which they had not known since
their first entrance into the Boarded-up House. It was no easy task to
remove the armfuls of books necessary to get at the door behind, and
then push and shove and struggle with the dusty shelves. In a
comparatively short time, however, the floor behind them was littered
with volumes hastily deposited, and the shelves for a space nearly as
high as their heads were removed. Then they tore at the mouldy shreds of
wall-paper till the entire frame of the paneled wooden doorway was free.
Handle there was none, it having doubtless been removed when the place
was papered. There seemed, consequently, no way to open the door. But
Cynthia was equal to this emergency.

"I've seen an old chisel in the kitchen. We might pry it open with
that," she suggested.

"Go and get it!" commanded Joyce, bursting with excitement. "I think
this is going to be either a secret cupboard or room!"

Cynthia seized a candle and hurried away, coming back breathless with
the rusty tool.

"Now for it!" muttered Joyce. She grasped the chisel and inserted it in
the crack, pushing on it with all her might. But the door resisted, and
Cynthia was just uttering the despairing cry,--

"Oh, it's locked too!" when it suddenly gave way, with a wholly
unexpected jerk, and flew open emitting a cloud of dust.

"Mercy!" exclaimed Joyce, between two sneezes, "That almost knocked me
off my feet. Did you ever see so much dust!" Snatching the candles
again, they both sprang forward, expecting to gaze into the dusty
interior of some long unused cupboard or closet. They had no sooner put
their heads into the opening, than they started back with a simultaneous
cry.

The door opened on a tiny, narrow stairway, ascending into the dimness
above!

CHAPTER XI

THE ROOM THAT WAS LOCKED

Before Cynthia could realize what had happened