"In your plane is an instrument which is the kernel of the scheme. It arrives here to-morrow. It's a device which shoots an invisible beam fifty miles into the air, a negative beam, in sympathy with the machinery on the torpedoes. Hay sets this device near the Slav headquarters. The torpedo squadron takes off from a few hundred miles behind here, flying in the direction of the heart of the Slav forces. When they run into the beam, their motive power is nullified, and down they fall. Crash! The Slavs are wiped out. Our troops charge forward in a grand attack; the Slavs, with no armament, no reinforcing troops, no supply of tanks and flame throwers, crumple. The invasion of America is put to an end!" Lance rose. His face was alight, his eyes burning with strong, unquenchable fire. "It's great, sir, great! It can't fail! By God, if it takes every last drop of my blood, I'll help Hay put this through!" Colonel Douglas extended his right hand and Lance's met it in a firm shake. In the thick silence they stood thus for some minutes. Then, without moving so much as a cheek muscle, the colonel whispered, his eyes tense: "_The door! Fling it open! I think someone's been listening!_" Lance switched his alarmed gaze to it. His muscles went taut. The next moment he had leaped half across the room, jammed back the lock, and ripped the door wide. At the other end of the dim passageway he glimpsed a scurrying figure! Lance sprang after it with a shout to Douglas. Tearing out his automatic, he flung a burst of lead at the figure, but that instant it wheeled and sped from sight down another passage. And when Lance got there, no one was in sight. * * * * * For awhile he probed around, desperately, but could find no sign of anything. The base slept. Sorely troubled, he returned to find the colonel just coming back from an equally barren search: "Don't think he heard much," said Douglas grimly. "It must have been that damned spy who's been getting information of our movements. I'll have the guards redoubled to prevent him from getting anything through." He smiled at sight of Lance's anxious face. "No need for too much worry, Lance! He couldn't have heard much--the walls are sound-proof and the door fairly tight. Now, you go and rip off some sleep! You need it! No more work for you till Wednesday night--you're too important!" Sleep! Lance only wished he could. But the thrill of what he'd just heard was too fresh, too new; the blood pumped surgingly through his veins; his brain whirled with the thought of the glorious enterprise he and Hay were aiding so vitally. Then, too, the night was humid and sweaty. For a while Lance lay on his cot, other sleeping figures to left and right of him, but his own eyes simply would not stay closed. Finally, after perhaps an hour of trying to doze off, he arose and, clad only in breeches and undershirt, wandered outside again with a cigarette glowing in his mouth.