Here the handiwork of man was in evidence. He was ascending into a space that had been hollowed out of the heart of a tree. Above his head was a small wooden trapdoor held in place by a wood slide or bolt. Releasing the bolt allowed the door to drop silently downward on hinges formed of stiff leather. A package fell into his hands, followed by a draft of air laden with the scent of summer woods. Pushing up his light Forrester recognized the hollow in the oak tree. He saw also that the upper side of the trapdoor was so prepared that it would seem like part of the tree to anyone investigating from above.
At last the most vital secret of the "Friends of the Poor" was in his hands—the method by which they had so mysteriously secured their toll under the very eyes of the detectives.
Forrester examined the small, flat package in his hand. Someone had placed a contribution in the tree that night. Then Forrester shivered. The scoundrels would come to collect at any moment! He was shut in at the far end of a narrow passage, the only way of escape leading back through the cottage where they would enter. If they met him here his end would be sure and his disappearance a mystery forever. Hastily he climbed down the ladder and was about to go when several objects drew his attention. The temptation to investigate these before he left was too strong to resist and Forrester lingered a moment or two longer.
All the paraphernalia that had made possible the ghostly illusions, which had frightened others and puzzled him, now lay revealed as nothing but mean claptrap. On the wall hung a group of rusty chains, a small megaphone for throwing the voice and an old locomotive bell. In one corner stood a tin similar to a paint can. This, Forrester found, contained a preparation commonly known as phosphorescent paint and a nearby glove, which smelled strongly of the substance, solved the riddle of the flaming hand which had impressed even the phlegmatic Green. The greatest curiosity of all, however, was a black tube standing against the wall. Forrester instantly remembered the appearance of something of this kind in Humphrey's photograph. On examination it proved to be a homemade periscope. By pushing it up into the opening in the oak tree it was probably possible for a person in the cave to ascertain what was occurring on the surface. Forrester did not wait to experiment, for he was sure that on the night of the Italians' visit someone was taking in the scene and the projecting end of the periscope had been picked up by the camera.
Forrester now hurried down the passage. Unquestionably he had lingered longer than was wise, and a quick escape was imperative. As he passed back through the passage Forrester's engineering training caused him to note certain things about him. Though the rocky walls and the sand beneath his feet were now dry, he saw indications that the cleft must serve as a drain for the neighborhood. In the winter it was probably a well; full of cold, stagnant water, which, he surmised, accounted for the peculiar inactivity of the "Friends of the Poor" after the winter rains and snow fell.
Before he reached the end of the passage Forrester was startled to hear a grating sound, followed by a slight thud.
Like a flash the truth came to him. Someone had discovered the moved sideboard and open door and surmising that the visitor was still in the cave had shut him in.
Forrester paused to reflect. It would be useless to try and force his way out. Even if he could get through the door, which he doubted, there was no telling how many of the band were in the cottage. Forrester was unarmed, as he had expected to deal only with Lucy, and a battle with more than one man would be an unequal struggle. To make matters worse, his electric lamp, which had been in constant use since he entered the cottage, now gave out. The bulb still glowed, but with a dull light that had no power. Forrester flung the lamp down and felt his way back toward the tree. He reasoned that as a package had been placed in the tree it was more than probable that detectives were concealed nearby. To climb into the opening in the tree, attract their attention by shouting, and then give directions for reaching him, seemed the only solution.
Continued calls, however, brought no response. Either there were no detectives there, or else his cries for help, which necessarily had to be subdued, were acting on superstitious minds and accomplishing just the opposite of what he intended—driving help away. Forrester ceased his calls and climbed slowly down into the cave once more.
Suddenly the place was brilliantly illuminated by the turning on of the electric lights over his head. The meaning of this was clear. The time had come when he must fight for his life and Forrester looked about for a weapon. There was nothing that would serve his purpose. Then he recollected the cylinders. Who knew better than these men their death-dealing power? With these cylinders in his hands would it not be possible to hold his assailants at bay—even to overcome them? Forrester dashed down the passage to reach the cylinders before his enemies. It was too late! As he rounded a slight curve in the rocky cleft he saw the figure of a man only a short distance away. Still there might be time. He could see the depression where the cylinders rested and the man was some distance on the other side. Forrester kept on, but his hopes fell as he saw the man reach the spot first and stop.