Wondering until they were fairly agape, Ulwin, Hal and Eph drew up at the cab door as Jack, after only a brief nod to them, opened the door and handed out Miss Daisy Huston. Lieutenant Abercrombie, having given his horse to a boy down the street to hold, now came forward, raising his hat, to take charge of the young lady. "Come along, Millard," called Jack Benson, quietly, and the prisoner got out, while the British officer stepped down the street with his fair companion to find another carriage in which she could return home. Inside Jack marched his prisoner up to the railing in one of the rooms. The young naval officer at once produced his credentials and displayed them to the police official in charge. "Now, with your permission, sir," Jack went on, courteously, "I will use your telephone, and inform the Navy Department of the prisoner who awaits their action here." Five minutes later this had been done. Benson turned to Lieutenant Abercrombie, saying: "I must apologize for not having thought to return your revolver as soon as we entered." "I would beg you to keep the weapon, dear old fellow, if it would be of any use to you," replied the British officer. And now Hal and Eph found chance to explain that they, worried by Jack Benson's disappearance, had at last started down to headquarters to see if they could learn of any mishap to him, or of any other explanation for his long absence. "Well, it's all over now," muttered Hal. "Millard--or Graves--or whatever other name the fellow may be using at this moment--is safe in a cell downstairs." "We thought, once before, that we had him bottled up safely," chuckled Lieutenant Jack. "Mr. Abercrombie, how am I ever going to express my thanks to you?" "I should feel extremely insulted, dear old fellow, if you thought it necessary to thank me," retorted the Briton, heartily. "It will be dark, soon," interposed Lieutenant Ulwin. "I suggest that the best thing any of us can do is to turn toward the club. I feel certain that the chef will have a famous dinner there to-night." "We haven't any evening clothes, either citizen or uniform, in Washington," interposed Jack Benson, who knew something of the formalities of the service during the dinner hour. "Come, just the same," begged Ulwin. "The members don't expect too much of fellows who are traveling." Jack was glad of the walk, because it helped to take the stiffness out of the knee that had been struck. "You let the cab driver go, did you!" asked Eph, as the submarine boys walked along together. "Yes," nodded Jack. "I had no orders concerning anyone like him. He's only some worthless character hired for the job. He didn't have any hand in the bigger job of collecting and selling harbor defense plans, you may be sure." As the party re-entered the club they found a large attendance. Nor was it many moments before a be-moustached German officer approached the group.