At length they found they had skimmed through all the volumes of "Punch," the last of which was dated 1860, and had them piled up on the floor beside them. This left a long space on the shelf from which they came, and the methodical Cynthia presently rose to put them back. As she fitted in the first volume, her eye was suddenly caught by something back of the shelves, illuminated in the flickering candle-light. "Joyce, come here!" she called in a voice of suppressed excitement. And Joyce, who had wandered to another corner, came over in a hurry. "What is it?" "Look in there!" Joyce snatched a candle and held it close to the opening made by the books. Then she gave a long, low whistle. "What do you make of it?" demanded Cynthia. "Just what it is! And that's as 'plain as a pikestaff'--a _keyhole_!" Cynthia nodded. "Yes, but what a strange place for it--back of those shelves!--" They brought another candle and examined the wall back of the shelves more carefully. There was certainly a keyhole--a rather small one--and around it what appeared to be the paneling of a door, only partially visible through the shreds of old, torn wall-paper that had once covered it. "I have it!" cried Joyce, at length. "At least, I think this may be an explanation. That's a small door, without a doubt,--perhaps to some unused closet. Maybe there was a time, when this house was new, when this room wasn't a library. Then somebody wanted to make it into a library, and fill all this side of the room with book-shelves. But that door was in the way. So they had it all papered over, and just put the shelves in front of it, as though it had never been there. You see the paper has fallen 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.