I. Vacation Plans II. What Came of Them III. Off to the Mountains IV. In the Burned Forest V. A Lost Opportunity VI. Trout Fishing in the Wilderness VII. The Forest Afire VIII. Making an Investigation IX. Charley Becomes a Fire Patrol X. An Encounter with a Bear XI. The Secret Camp in the Wilderness XII. On the Trail of the Timber Thieves XIII. Spying Out the Land XIV. The Trail in the Forest XV. The Telltale Thumb-Print XVI. Good News for the Fire Patrol XVII. An Accident in the Wilderness XVIII. The First Clue to the Incendiary XIX. The Forester's Problem XX. Charley Wins His First Promotion XXI. A Trouble Maker XXII. Charley Finds Another Clue XXIII. A Startling Discovery XXIV. Checkmated XXV. The Crisis XXVI. More Thumb-Prints XXVII. Trapped XXVIII. Victory The Young Wireless Operator--As a Fire Patrol Chapter I Vacation Plans Charley Russell sat before a table in the workshop in his father's back yard. In front of him were the shining instruments of his wireless outfit--his coupler, his condenser, his helix, his spark-gap, and the other parts, practically all of which he had made with his own hands. Ordinarily he would have looked at them fondly, but now he gave them hardly a thought. He was waiting for his chum, Lew Heinsling, and his mind was busy with the problem of his own future. Charley was a senior in high school and was pondering over the question of what the world had in store for him. While he sat meditating, Lew arrived. In his hand was a copy of the <i>New York Sun and Herald</i>. He held it out to Charley and pointed to the marine news. "The <i>Lycoming</i> reaches New York to-day," he said. "Roy will send us a wireless message to-night. Gee! I wish we had a battery strong enough to talk back." But Charley paid slight heed to the suggestion. Instead he said: "Roy Mercer's a lucky dog. Think of being the wireless man on a big ocean steamer when you're only nineteen. I wish I knew what I am going to do after I graduate from high school." Roy Mercer, like Charley and Lew, was a member of the Camp Brady Wireless Patrol. With his fellows he had taken part in the capture of the German spies who were trying to dynamite the Elk City reservoir and so wreck a great munitions centre during the war; and with three other members of the Wireless Patrol, especially selected for their skill in wireless, he had later gone to New York with their leader, Captain Hardy, to assist the government Secret Service in its search for the secret wireless that was keeping the German Admiralty informed of the movements of American vessels.