midnight
Pierre and Pierrette longed to tell Mademoiselle and the Doctor their secret , but Uncle Sam had told them to share it with no one but their parents , and they knew obedience was the first requisite of a good soldier ; so they said nothing , and nearly burst in consequence . They went no more to the meadow after cress , however . Mother Meraut saw to that . If they had gone there on the morning of the next day but one after their encounter with the spies , they would have had a still more thrilling experience , for at midnight Uncle Sam , Jim , and the Captain had quietly stolen away from camp and hidden themselves in the straw . There they stayed until in the gray of the early dawn they saw a boat come up the river , and the slouching figure of the spy stalk across the meadow to his rendez-vous under the shed . They stayed there until the soldier appeared , and until they had heard with their own ears the plan for signaling the German airplane that night , and for giving information which would en able the aviator to blow up their stores of powder and ammunition . Then , suddenly and swiftly , at a prearranged signal , the three men sprang from the straw , and the astonished spies found themselves surrounded and covered by the muzzles of three guns .