"Worse than deserters! They're traitors!" said Jimmy. "And we left two German spies back in the cave. We've found out the secret of the smoke signals. We'd like to report to the officer commanding this sector, and deliver our prisoners." "Smoke signals, eh?" exclaimed Sergeant Walton, who had charge of a party out in search of possibly forgotten wounded men. "That's queer. A squad of our boys, several squads, in fact, are out looking for two of the smoke signal machines which the signal corps reports missing since last night." All eyes were turned toward the Bixtons. But they maintained their policy of silence. "Come on, I'll take you to the K. O.," offered the sergeant. This was done, and Roger and Jimmy soon turned over their prisoners and gave an account of the whole proceeding from the time they were knocked senseless until they attacked and caught the German spies. Then, after the boys had accurately described the location of the cave, a party was sent there to bring back the two Huns. The one had considerably improved, being but stunned, but the other never regained consciousness, and died that night. But with the capture of the Bixtons and the finding of the papers which they had prepared to give the Germans in exchange for gold, the whole secret plot was exposed. The two scoundrels had, more than once, sent up the smoke signals which enabled the Boches to locate hidden batteries or machine-gun emplacements. And to work their latest plot the brothers had taken into the woods one of the new smoke caldrons. They had sold their honor--and had brought death to many of their companions through greed for gold. It was during one of their secret conferences with the spies that the Khaki Boys had seen the Bixtons in the dugout. And only for their capture in the cave a grave disaster might have befallen the American army through the traitorous conduct of the Bixtons. For they had planned, by sending up more smoke signals from another machine which they had taken to the woods, to disclose the location of a great battery of new, big naval guns, designed to smash the German lines. The successful attack of Roger and Jimmy came at just the right time. The plot was foiled and the plotters caught. And, to end an unpleasant subject, it might be said here that the Bixtons were tried by court martial shortly afterward, found guilty, and executed, as was the remaining German spy. "Well, that's over," said Roger, a week after their strenuous time in the cave and on the day of the traitors' execution. "It was tough, but it had to be done. And now I hope they'll let us get back to our old Five Hundred and Ninth." "I'm with you there!" cried Jimmy. "I want to see Bob and Iggy. I don't suppose there's any news of Franz yet." "Maybe not, but I hope there is," sighed Roger.