“Listen, girls. It must be near the chimney. Probably some stovepipe hole leads into this flue, and the draught carried the sound downward. All we have to do is to make another search upstairs near where the chimney passes through.” “Simple as a problem in geometry,” murmured Alice, who detested the study. “Lead on, Nat!” “Will you come?” asked breath-of-the-pine-tree, looking at her companions. “Well, I suppose it might be some one in trouble,” agreed Mrs. Bonnell. “But— Oh, well, I guess there are enough of us,” and she picked up from the floor a stout cudgel. “We had better arm ourselves,” she added. “There may be——” “Rats!” broke in Marie. “She is fined a pound of candy for saying that!” exclaimed Natalie. “Come on,” and she led the way. Now that they had some definite plan of searching they felt more assured of success. There were two upper stories to the old mill, but the girls had given only a casual glance around the third one, as it was so dark and gloomy that they did not fancy remaining in it. Now it became practically certain that, if there was a secret room, it would be on the third floor, for a look around the place where the big chimney passed through the second floor, showed that there was no room for a hidden recess. “We’ve got to go up there,” said Natalie firmly, as they came to a pause at the foot of the second flight of stairs. “Hark!” cautioned Marie. As they listened they heard again the sound of the crying voice. “Who is there?” called Mrs. Bonnell sharply. There was no answer. Natalie said afterward that she did not know how she got the courage to do it, but she started up the stairs, and the others, after a moment of hesitation, followed. Natalie hurried on. She saw a small window, through which the light streamed, filtering in between cracks in the ancient shutter. With the stick she carried, she shoved this back, letting in a beam of sunlight. There was a flutter of wings, and something flew around the heads of the Camp Fire Girls. “Oh!” screamed Mabel and Alice. “They are only bats!” called Mrs. Bonnell. “Oh, but if they get in our hair!” murmured Mabel, crouching down. “It’s gone out of the window,” the Guardian assured them. Natalie was busily scanning the wall near the chimney. The girls stole to her side. “Listen!” commanded Natalie in a whisper. Faintly they heard a moan. It seemed to come from inside the big chimney. Natalie took a step toward it. Her eyes roved over the ancient paneling. One section seemed to be darker colored than the rest. Natalie pressed on this, hardly knowing why, for it bore no semblance to a door. But she nearly stumbled and fell as the panel unexpectedly gave way, and there was disclosed the secret room they had been looking for. CHAPTER XXXII HADEE