A loud knock came at the door. The girl leaped away, and her eyes shone through the slits in her mask like half-hidden incandescent lights. “There! I told you!” she gasped. “Where can I hide?” In a corner of the dark box Nick Carter’s voluminous light overcoat hung on a peg. The girl slipped behind the coat and was completely hidden. Unless some one should come and make a thorough search, there was no fear of her being discovered. “I don’t know who Marcos is,” thought Nick. “But it seems as if I am to assume his name for the present. So here goes. I need a little excitement, to make up for my disappointment over Martin.” When he swung open the door, all he saw was a liveried attendant, with a silver salver. On it was a small coffeepot, with sugar, cream, and a cup and saucer. “Who ordered that?” demanded Nick. “I have been sent to ask if you would like a cup of coffee, your highness,” said the man imperturbably. The attachés of the Hotel Supremacy are used to meeting highnesses, kings, lords, tycoons, viceroys, effendis, and so forth. There is nothing in the way of a title that can disturb them. If the Ahkoond of Swat came along, they might wonder to find that historical personage still alive, but they would announce him as coolly as they would “Mr. Jones, of Penn Yan.” “I’m a ‘highness,’ am I?” thought Nick. “Marcos must be somebody worth representing, anyhow.” He made a sign for the man to put the tray on the small table that was part of the furniture of the box. When he had gone out and the door had closed, the girl came out from behind the overcoat, and put her hand on Nick’s arm just as he was reaching for the coffeepot. “You don’t believe me?” she protested, with a catch in her voice that showed she was hurt. “I tell you I saw Solado whispering to that man who brought in the coffee, and Solado gave him a yellowback bill. That coffee is drugged. They are going to prevent your getting out of New York somehow.” “Even if they have to dope me?” smiled Nick Carter. “Well, I assure you I had no intention of drinking that coffee. It is not my habit to eat or drink anything that comes to me with so much mystery.” “There is no mystery in it to me,” she rejoined. “I know those men, and so ought you, Marcos--I mean, your highness.” Nick Carter laughed softly, as he put his hand to his mask. “You will insist that I am somebody else,” he said. “The best thing I can do is to let you see my face.” The black satin mask was off with one twitch, and the girl gazed at him steadily for several moments. It seemed as if she could hardly believe the evidence of her own vision. “Well?” queried Nick. “You are not Prince Marcos. But you are wonderfully like him. You might be twin brothers, except that your eyes are a little darker than his, and your mouth is firmer. But the shape of your face, your expression, and even your voice are almost identical. It’s marvelous!”