"I don't know," Joe answered. "I discovered him in the battery room. We fought in the dark." With the aid of the others he raised himself to a sitting posture, then stood up and walked rather unsteadily across the room, took a long quaff of cold water and dropped heavily into Lieutenant Mackinson's Morris chair. At the same time he gazed for the first time at what he had been holding tightly clutched in his right hand ever since the knockout blow had been delivered. The other three also were staring at it in open amazement. "What is it?" asked Joe, as the lieutenant crossed the room and took the thing from him for a closer examination. "What is it?" Lieutenant Mackinson repeated. "Why, lad, this is the German iron cross! Tell us what happened here." With the young officer seated before him, and his two pals standing at either side of his chair, Joe, quietly, quickly and as carefully as he could, gave them every detail of the occurrence, from the moment he had first heard sounds in the battery room, to the time that the other man ran away and he lapsed into unconsciousness. While Joe was relating his story the lieutenant examined and re-examined the iron cross, the bit of broken chain still attached to it, and the piece of brown woolen army shirt which the lad had torn away with it. As the latter finished, the young officer hurried into the battery room, accompanied by Slim, to make a survey there. In ten minutes he returned, his face pale, his jaws clenched. "There must not be a word of this to anyone," he warned them. "I am going to report to the captain at once. Someone has been tampering with the batteries, and he had with him a portable wireless which he evidently intended to attach." "You're the original little discoverer, all right," said Slim in open admiration, addressing Joe as the lieutenant hurried from the room. "And you certainly were game, to take the beating you did." "Yes, he punished me some," Joe admitted. "But I got in a little work on him, too. The only trouble is that I'm afraid I didn't blacken an eye, or break a jaw, or otherwise do any damage that might be apparent and so lead to the fellow's discovery." "The nerve of it, though!" broke in Jerry. "A German spy, doubtless masquerading as an American soldier, and right here on a United States transport loaded with fifteen hundred soldiers and tons of guns and ammunition." "Yes," said Joe contemplatively, "that's the very serious part of it all--the fifteen hundred soldiers and tons of guns and ammunition." "Sh-h-h-h!" Slim, who was standing nearest the door, had heard footsteps. A moment later the lieutenant reappeared, accompanied by the captain of the _Everett_. When the boys had been presented, the captain abruptly requested Joe to repeat every detail he had told Lieutenant Mackinson. As he did so the captain gazed compassionately upon his injuries. "And where is the instrument that you discovered?" he asked of the lieutenant when Joe had concluded.