Grace winked at Elfreda and changed the subject. After the dishes were washed and put away the two girls sat down to study their German, which they had been studying for some time. Since coming to the Rhine Grace had taken advantage of every opportunity to speak German, feeling certain that it would prove to be a good investment. Her knowledge of the language was destined to be very useful to her in the near future. They turned in shortly after nine o’clock, Elfreda to go to sleep, Grace to lie awake and think. Before getting into bed she had whispered to Miss Briggs not to be alarmed if she were awakened suddenly in the night with a feeling that something was wrong in the room. “That something will be only unimportant little I. I may be walking in my sleep for several nights to come.” After ages of effort to keep heavy eyelids from falling, Grace was rewarded by hearing the trap raised in the adjoining room and light footsteps descending the cellar stairs. The Overton girl crept under the bed at the sound of the opening trap, and ere the footsteps had reached the cellar she had pulled aside the carpet just far enough for her purposes, removed the cardboard and pressed her ear to the hole in the floor. Every sound down there was almost as audible to her as if she had been in the cellar. “Now for the test of my plan,” she told herself. Significant sounds were borne to her ears, then a human voice, speaking in a low guarded tone, drifted up through the hole in the floor. What she heard amazed even Grace Harlowe. She learned too that one mouse had walked into the trap that had been cleverly set for it. CHAPTER XXII “CAPTAIN” GRACE DECIDES TO ACT When finally Grace Harlowe had replaced the carpet and crawled out, her face wore a serious look. She stood in the middle of the floor for a long time, thinking over what her resourcefulness had produced in the way of definite information. “I shall at last have to take Elfreda into my confidence. The time to act is at hand,” she muttered. “This is bigger than even I, with all my suspicions, dreamed. The Intelligence captain surely will have a good laugh at my expense when I tell him what I have discovered.” Grace grinned mirthlessly and returned to bed and went to sleep. “I have something to tell you this morning, Elfreda,” she whispered at the breakfast table. “Don’t ask me now. I haven’t decided where or when, but I shall think it over between now and the time we finish breakfast. Remember, the walls have ears. To-night something will be doing.” Elfreda looked at her curiously, but Grace merely kissed her and proceeded to put the breakfast on the table. After finishing, Grace said she thought their best plan was to stroll down to the river, where they would be certain to be alone. On the same seat where she had talked with Captain Boucher, Grace told her companion all that she had learned up to that moment. Elfreda’s amazement was for the moment beyond words.