"She must have dropped it accidentally, perhaps when she took it off, and it rolled under the bed. In her hurry she probably forgot it," said Joyce, laying it beside the curious disk they had raked from the fireplace. "Isn't it a beauty? It must be very valuable." Cynthia bent down and examined both articles closely. "Did you notice, Joyce," she presently remarked, "that those two things are exactly the same shape, and almost the same size?" "Why, so they are!" exclaimed Joyce. "Oh, I have an idea, Cynthia! Can we open the locket? Let's try." She picked it up and pried at the catch with her thumb-nail. After a trifling resistance it yielded. The locket fell open and revealed itself--empty. Joyce took up the disk and fitted it into one side. With the gold back pressed inward, it slid into place, leaving no shadow of doubt that it had originally formed part of this trinket. "Now," announced Joyce, "I know! It was a miniature, an ivory one, but the fire has entirely destroyed the likeness. Question: how came it in the fire?" The two girls stood looking at each other and at the locket, more bewildered than ever by this curious discovery. Goliath, cheated of his plaything, was making futile dabs at the dangling velvet ribbon. Suddenly Joyce straightened up and looked Cynthia squarely in the eyes. "I've thought it out," she said quietly. "It just came to me. The miniature was taken out of the locket--on purpose, _to destroy_ it! The miniature was of the same person whose picture is turned to the wall down-stairs!" CHAPTER VI JOYCE'S THEORY "Cynthia, what's your theory about the mystery of the Boarded-up House?" The two girls were sitting in a favorite nook of theirs under an old, bent apple-tree in the yard back of the Boarded-up House, on a sunny morning a week later. They were supposed to be "cramming" for the monthly "exams," and had their books spread out all around them. Cynthia looked up with a frown, from an irregular Latin conjugation. "What's a _theory_?" "Why, you know! In Conan Doyle's mystery stories _Sherlock Holmes_ always has a 'theory' about what has happened, before he really knows; that is, he makes up a story of his own, from the few things he has found out, before he gets at the whole truth." "Well," replied Cynthia, laying aside her Latin grammar, "since you ask me, my theory is that some one committed a murder in that room we can't get in, then locked it up and went away, and had the house all boarded up so it wouldn't be discovered. I've lain awake nights thinking of it. And I'd just as lief _not_ get into that room, if it's so!" Joyce broke into a peal of laughter. "Oh, Cynthia! If that isn't exactly like you! Who but you would have thought of such a thing!" "I don't see anything queer about it," retorted Cynthia. "Doesn't everything point that way?"