"Footprints of a pair of heavy boots," announced Hippy. "The impression they have left in the moss is unmistakable. This looks as if he had rested his gun-butt here," he added, laying a finger on another depression in the moss. "I do not think so," said Grace, after examining it critically. "I should say that the man made that second impression with the toe of his left boot. By looking at the impression of the right boot you will observe that it sunk in deeper, meaning, probably, that he threw his weight on the right foot and took a step forward with the left, only the toe of which was on the ground as he leaned forward to peer into our camp." "'Ma'velous! Ma'velous, Sherlock!' How do you do it?" chortled Hippy. "Elfreda, please fetch my revolver. I am going to follow out this trail a little way. Perhaps I may discover something," said Grace. Hippy said he would accompany her, but Grace shook her head. "Please stay here and look out for the camp. If I need you I will shoot three times." "I wish you would not go out," urged Elfreda. "What is to be gained? Nothing, and there may be much to lose." "Grace has made up her mind to go, so you might as well save your breath, J. Elfreda," said Anne. "Some persons are so stubborn," murmured Emma. Grace smiled and nodded, then parted the bushes and stepped in. She was lost to their sight in a few seconds, moving on through the tangle of bush and vine without causing a rustle that their listening ears could hear. "Fine, fine!" observed Miss Briggs. "We surely have made a most excellent start." "Cheer up. The worst is yet to come," reiterated Hippy. "Keep your ears open. I'll be back in a moment." Hippy ran to his tent, returning with his heavy army revolver strapped to his waist. "What are you going to do?" questioned Anne. "Grace said you were not to follow her." "I'm not going to. I have merely prepared myself in case she signals for me. All hands keep quiet and listen. Stop that noise!" warned Hippy as Wash struck a chord on his harmonica. "Nora, if he sounds another note, take the infernal music box away from him. I--hark!" A sharp report startled the Overland girls. "That wasn't Grace's revolver," announced Lieutenant Wingate, leaning forward in a listening attitude, but before the words had left his lips, in fact, instantly following the first shot came a heavy report, a bang that woke the mountain echoes. "That's Grace! That's a service revolver," cried Hippy. "They're at it!" exclaimed Elfreda, as three more shots in quick succession, two of them from Grace's revolver, were fired. "Run, Hippy!" cried Nora Wingate. "Shake your feet!"