"Shall we walk or hail a taxi?" asked Bob, as they stepped out into the street. "The full moon is on the job to-night. We can see our way along even though this burg is shy on street lights." Since the beginning of the war Paris had shown few street lights after nightfall. Due to the fiendish Boche practice of making nocturnal air raids for the purpose of dropping bombs, principally upon defenseless women and innocent little children, every possible precaution had been taken to guard this city against the inhuman cruelty of an ignoble foe. "We'd better ride," decided prudent Roger. "It will be quicker and we'll run no chance of losing our way. Here comes a taxi now. Hail it, Blazes. You know how to _parlez-vous_." Immediately complying, Jimmy signaled the driver of the machine. A moment's shrewd bargaining with the latter regarding the fare to the station, and Jimmy motioned his bunkies to step into the motor car. None of the five observed, as they entered the vehicle, that a man had emerged from the shadows of a neighboring building and signaled another taxicab just driving up to the curb. In consequence, they were not aware that the second taxicab was sedulously keeping on the trail of their own. CHAPTER IV AN UNSEEN FOE It was not a long journey to the station for which the Khaki Boys were bound. During the ride they had plenty to say in regard to the interesting trio they had left behind them. What had been rather a dull afternoon had suddenly turned into a red-letter evening. Not only were they jubilant at having again encountered the Twinkle Twins. They had also met one of the great heroes of France, and they could not readily get over it. Arrived at the station, they were obliged to spend half an hour there before getting a train back to camp. Still absorbed in enthusiastic talk concerning their absent friends, they were not impatient over this little wait. With the train on time, the five Brothers calculated reaching camp in good season. Once there a few moments' brisk walking would see them safely back in quarters. All now being non-commissioned officers they had found it comparatively easy to make arrangements to be together. They were now well aware, however, that when they reached a village back of the firing line this state of affairs could not continue. Each would probably be quartered in a separate residence with a number of privates in his charge. "We've barrels of time," announced Bob, as the train stopped in front of the camp station. "Where's our jailer? It's time he came and let us out of the jug." By "jug" Bob humorously referred to the compartment which the guard had locked at the beginning of the journey. As it happened, the guard was at that moment engaged in unlocking another compartment from which issued a solitary man, heavily bearded, his hat pulled over his eyes.