The effect of the drug having worn off, Mark stirred uneasily, and started up. He heard Jack's cry, and uttered a half-articulate answer. In an instant the man was at his side, and had quickly gagged him. This had the further effect of awakening the unfortunate lad; and he struggled to loosen his bonds, but they were too strongly tied. He endeavored to answer Jack, but only a meaningless mumble resulted, for the gag was effective. "All you have to do is to keep quiet," urged the man, as he knelt beside Mark in the darkness. "As soon as your chum goes, I'll take that thing out of your mouth, and give you something to eat." Jack's voice died away, and presently, as the ears of the man told him, the boy left the old house. Waiting some time, to make sure that he would not return, the man removed the knot of rags from Mark's mouth, and slightly loosened his bonds, first warning him, however, that if he attempted to escape he would be harshly dealt with. "But what right have you to keep me here?" demanded the youth. "Who are you, and what have I done to you, that you should treat me this way? Are you crazy? Don't you know that you are liable to arrest for this?" "No one can arrest me," boasted the fellow. "But why have you made me a prisoner?" demanded Mark. "For reasons of my own. You'll see very soon." "But what have I done to you?" persisted the lad. "I never saw you before, that I know of, unless you are the man who sent me the note, and who ran when my chum and I came to the bridge to meet you." "I'm the man," was the answer, with a chuckle. "Then you must be the one who tried to wreck our projectile," went on Mark. "Yes, I did that, and now I am sorry for it, for I have thought of a much better scheme for getting even, and having my revenge on you." "But why do you want to be revenged on us?" "Because of what you have done!" and the man's voice took on an ugly tone. "But what did we do?" begged Mark. "You'll know soon enough," was the answer, with a cunning laugh, and then Mark was sure he had to deal with a lunatic. He ceased his struggles to loosen the bonds, and resolved to meet cunning with cunning. He would bide his time. "Will you promise to be quiet, and not kick up a fuss if I get you something to eat?" asked the man. "Yes; but I'd rather have a drink of water first. I feel sick." "Very well, you shall have some water. I'll have to go out and get it, but I must first blindfold you, so that you will not discover the secret of this room." Mark could not help himself, for he was bound, and when the man had tied a handkerchief over his eyes, Mark heard his captor moving about.