"Smith," said Thompson, "how did I injure my hand?" "Why," said Smith, "you miscalculated, and instead of putting it against Black's head, you put it against the door." Thompson turned to Black. "Is that true?" he asked. "Yes," replied Black. Thompson turned to Lord Hastings. "That should be enough, sir," he said quietly. "What is the meaning of this?" demanded Lord Hastings, looking from one to the other of the three men. "It's plain enough," said Jack stepping forward. "Thompson and Black were settling an argument of some sort by the use of the fists. And Smith, I take it, was the referee. Am I right?" "Right you are, sir," replied Smith. "But we didn't----" "Never mind, never mind," said Jack with a wave of his hand. "All of you line up there alongside Brice." He turned to Frank and Lord Hastings. "We are on the wrong track," he said. "So it seems," replied Lord Hastings, "but appearances were against him. We'll have to look further." One after another the members of the crew were examined, but in spite of the best efforts put forward by Lord Hastings, Jack and Frank, not one of them could be tripped up. "But it must have been one of them," said Frank, after all had been examined and given satisfactory accounts of themselves. "It must be one of them. I certainly didn't dream I was attacked. But who was it?" "Can there be a stowaway aboard?" asked Jack. "I never thought of that," exclaimed Frank. "Shall I have the ship searched, sir?" "Immediately," ordered Lord Hastings. "We'll leave Johnson here to guard these men, while we make a thorough search." From stem to stem they searched the little submarine. Not a single movable obstacle but what they moved. It was as systematic a search as it was possible to conduct, but there was no sign of a stowaway. "Well, there is no one here," said Frank, when the search had been concluded. "Therefore, it must have been a member of the crew." They went back to Lord Hastings' quarters, where Johnson still stood on guard. Lord Hastings looked them over carefully, then spoke. "Men," he said, and his voice was very grave. "Some place on this vessel there is a traitor. We have searched high and low for some sign of a stranger, but we could find no one. Therefore, the spy must be among you. Will he step forward and save his companions from the finger of suspicion?" Not a man stirred. "Then----" began Lord Hastings, but he was interrupted by a sudden motion of the vessel, which seemed to be flying up through the water. Up to this time it had been perfectly stationary. "What's the meaning of that?" cried Lord Hastings when he had recovered his balance. "I should say someone was forcing the water out of the tanks, sir," replied Jack calmly. "But every man is in this room," replied the commander. "You forget the stowaway, sir," said Frank. "But there is no stowaway." "There must be a stowaway! How else do you account for this? The vessel could not do it by itself."