"A man is discovered at night in the battery room of the wireless department of this ship, clearly upon an unfriendly mission," said the captain, half to himself and half for the benefit of the others, summing up the evidence thus far known to them. "He gives battle to the man who discovers him, and finally succeeds in knocking that man out and escaping. But he leaves behind him a portable wireless instrument, and a German iron cross, with two bits of the chain attached. "A few hours later that same night he returns to the battery room and succeeds in recovering the portable instrument. "To-day Lieutenant Mackinson, while pursuing an investigation of the affair, is shoved into a closet and only escapes death from suffocation by making himself heard as he telegraphs for help over a steam-pipe. "It must have been while we were rescuing the lieutenant that the same man again enters the wireless room and leaves there this chain, which had been attached to the iron cross, and also this note of warning. "The impudent effrontery and the cunning treachery of this man constitute him a menace to every other person aboard this ship. We are not safe while he is free. "This German spy must and shall be found." CHAPTER VIII THE DEATH OF THE SPY The inability of Lieutenant Mackinson to add a single word of further information to what he had said as he regained consciousness on the promenade deck increased the mystery. The young lieutenant, it seemed, had been following a trail which he believed was leading him closer and closer to the object of the hunt, and it was in forging the links of this chain of circumstantial evidence that the young officer was led into the lower depths of the ship. "From a sailor who did not know why I was inquiring," he told the captain, "I learned that on the night the unknown man invaded the battery room this sailor had seen another member of the crew, presumably from the engine or boiler room, throw aside something as he hurried along the passageway leading from the wireless room. He was in his undershirt. "The sailor said he was about to investigate when he saw us come along, and you stooped to pick up whatever it was that had been thrown away. "While I was talking to him another member of the crew, evidently also from the boiler or engine room, brushed by us. He had disappeared when the sailor said to me, 'I think that was the fellow--the one that just went by.' Not wanting to arouse his suspicions, I ended the conversation with a casual remark, and then strolled away until I was out of the sailor's sight, and then hurried as fast as I could toward the engine room. "I do not know that part of the ship well, and it was very dark down there. I was groping my way along when I thought I heard steps just ahead of me. I stopped to listen, and when the sound was not repeated I proceeded onward.