Thus duly squashed by her own chum, Dulcie made no further plea; she only banged the door in reply, and they could hear her footsteps stumping slowly and heavily upstairs. In a few moments, however, she descended with a much swifter motion, and, looking pale and frightened, burst into the schoolroom.
"There's somebody or something inside the barred room," she gasped. "It—whatever it is—it's tapping on the door. I daren't go past."
Both Deirdre and Gerda rose to the rescue, and—three strong—the girls ventured to investigate. With a few pardonable tremors they drew aside the curtains that concealed the door of the mysterious room. There was nothing to be seen or heard, however. The iron bars had not been tampered with, and all was dead silence within.
"Your nerves are jumpy at present, and you'd imagine anything," decided Deirdre.
"I didn't imagine it. I really heard it. I tell you I did. Oh, I say! There it is again!"
Instinctively the girls clung together, for from inside the door certainly came the sound of rapping, not very loud, but quite unmistakable.
"Who's there?" quavered Deirdre valiantly. But there was no reply. "If you want help, speak," she continued.
The three held their breath and listened. Dead silence—that was all, nor was the rapping repeated.
"I've heard it before," whispered Gerda.
"When?"