"The old codger seems mightily pleased over something," mused Frank, "and I'm willing to bet a reasonable amount it isn't over any schemes for the betterment of mankind. I may do him an injustice, but I don't think his genial Hun nature is inclined exactly in that direction."
He gave little further thought to the chance meeting, his mind being busied with speculations as to what he might find in the mysterious alley. The weather was very mild, and he knew the sheet of ice and snow that had covered the ground on his previous visit would not now exist to baffle him. But he did not want to enter the alley until darkness had fallen to offer him concealment, so abated his usual brisk pace to a mere saunter, and took careful note of the attitude of the people he passed. The streets were quiet enough, but the faces of the inhabitants were sullen and hostile, and Frank could read enmity in the glances cast at him.
"They love the Americans about as much as they love sunstroke," he meditated. "But it doesn't matter much what they like, because they'll take just what's handed to them. But it's the lower elements and the revolutionists who are making most of the trouble, and I'm a lot mistaken if their headquarters aren't in the neighborhood of that blind alley. Well, anyway, I'll know more about it when I get through my privately conducted explorations this evening."
He stopped in a small restaurant and ordered a light meal. By the time he had finished this it was nearly dark, and he set out for his objective without further delay.
He shortly reached the entrance to the alley, and, after casting a searching glance about him to make sure that he was unobserved, he slipped cautiously into the place.
"It ought to be a lot easier for me to locate that trap door now than it was when I was here with Bart," he thought. "There's no ice now, and if there is a door, I'll be bound to find it."
He proceeded cautiously up the alley, taking every precaution to avoid noise, and soon reached the blank wall that had so baffled him and his friends on a previous occasion. He drew a flashlight from his pocket, and when he thought he was close to the place where he and Bart had previously located the door he cautiously played the tiny spot of light over the ground. At first he thought he must be mistaken, as this part of the alley seemed to be like all the rest. But, looking closer, his heart leaped as he made out the outline of a heavy iron ring, lying flat in a recess in the pavement, and almost covered with gravel and dust. So cunningly was it concealed that it would inevitably have escaped observation unless one were actually looking for it.
"There's a trap door here, all right," he exulted. "Now, I wonder if I can get in, or if it will be fastened from the inside. Here goes to find out."
With the thought, he worked the iron ring loose from the dirt, set himself for the effort, and gave a tentative tug. The door did not give a particle, and he tried again, this time putting every ounce of his strength into the effort. The door gave a little, but with all his strength Frank could not lift it more than an inch or two. He tried again and again, but with no better result, and at last, to his great disappointment he was forced to give over the attempt for the time being.
"Guess this is more than a one-man job," he thought to himself. "What I'll have to do is to bring Bart and Billy here to-morrow night, and I think the three of us can lift the door easily. I've made one big step, anyway, for now I know there is really a trap door here, and before we weren't sure of it."