Roger let a faint gleam escape from between two fingers which he pressed over the small bulb of his pocket flash lamp. He directed this gleam into the dugout, and then he and his chum received another surprise. For the place was empty. The four men--two soldiers and two civilians--had disappeared! As Jimmy and Roger stood in the tunnel, a few feet away from the door leading into the dugout, from behind them came Bob's voice. "Say!" he whispered, "are you fellows going to stand there chinning all day? We want to get Iggy somewhere so we can see what the matter with him is! What's the row, anyhow--why the traffic hold-up?" "Something queer going on here, that's all," answered Roger. "Come on now--the way's clear. Wow! Hear that gun!" "One of our big new ones," remarked Jimmy, as the concussion shook the tunnel and rattled down particles of dirt from the sides and roof. "If there's fighting going on we ought to be in it!" exclaimed Franz, as he and Bob started on again with the disabled Iggy. They could see the dim gleam of Roger's lamp ahead of them. "Oh, we'll get in it as soon as anyone," remarked Jimmy. "But first we want to find out what's going on here. Come on, fellows. We can get out of the tunnel and into this dugout, anyhow. This place seems to be all right. I know my way out. The cave-in didn't extend this far back." This was true. The big shell that had brought their rest dugout down about the heads of the Khaki Boys had done no damage here. One end of the tunnel--that nearest the big underground shelter--was partly demolished, but the end connecting with the second dugout was not disturbed. Into this dugout, then, went the five Khaki Boys, Iggy shuffling along by putting his arms over the shoulders of Franz and Bob. They had been obliged to proceed sideways in single file along the narrow tunnel, but the dugout was large enough to accommodate a dozen or more. "They aren't here!" exclaimed Jimmy, as he quickly looked around the place, Roger having relighted the candle in the bottle. "Who aren't here?" Franz demanded. "The four men we saw when we stopped so suddenly," Jimmy explained. "They've gone!" "Where?" Roger wanted to know. Jimmy pointed to a rude door leading out of the tunnel. It was answer enough. "Say, you fellows act as though there was a dark mystery here," complained Bob, as he helped Iggy to a seat on a box. "I'm beginning to think there is," was Jimmy's answer. And hardly had the words passed his lips than from the door leading out of the dugout came a voice saying: "Come on now! We can get 'em this way, I guess!" The four Khaki Boys drew their revolvers and stood tense and waiting, forming a protecting screen in front of Iggy. CHAPTER IV RECOGNITION