Outside, somewhere, a sound had made itself heard. Then on the porch, a loose board creaked. Gabriel sprang to his feet. The others stood up and faced the door. "In heaven's name, what's that outside?" demanded Craig. On the instant, a heavy foot crashed through the panels of their door. The door, burst open, flew back. In the aperture, stood a man, in aviator's dress, with another dimly visible behind him. Both these men held long, blue-nosed, oxygen-bullet-shooting revolvers levelled at the little group around the table. "My God! Air Trust spies!" cried Grantham, pale as death. "Hands up, you!" shouted the man in the doorway, with a wild triumph in his voice. "You're caught, all of you! Not a move, you ---- ---- ----! Hands up!" CHAPTER XXXI. ESCAPE! Quick as thought, at sound of the imperative summons and sight of the levelled weapons, Gabriel swept up most of the papers and crammed them into the breast of his loose flannel shirt, then dashed the lamp to the floor, extinguishing it. The room grew dark, for now the fire had burned down to hardly more than glowing coals. There was no panic; the men did not curse, neither did the women scream. As though the tactic had already been agreed on, Craig tipped the table up, making a kind of barricade; and over it Grantham's revolver, snatched from his belt, spat viciously. It all happened in a moment. The foremost spy grunted, coughed and plunged forward. As he fell, he fired his terrible weapon. The bullet--a small, thin metal shell, filled with a secret chemical and liquid oxygen--went wild. It struck the wall, some feet to the left of the fireplace, and instantly the wood burst into vivid flame. Flesh would crisp to nothing, solid stone would crumble, metal would gutter and run down, under that awful incandescence. Again Grantham's revolver barked, while Bevard tugged at his own, which had unaccountably got stuck in its holster. But this second shot missed. And even as Grantham's bullet snicked a long splinter from the door-jamb, the second spy fired. Brevard's choking cry died as the gushing flame enveloped him. He staggered, flung up both arms and fell stone dead, the life seared clean out of him, as a lamp sears a moth. Gasping, blinded, the others scattered; and for the third time--while the room now glowed with this unquenchable blossoming of flame--Grantham shot. The spy's body burst into a sheaf of fire. Up past the lintel streamed the burning swirl. Mute and annihilated, his charred body dropped beside that of his mate. The total time from challenge to complete victory had not exceeded ten seconds. "I exploded some of his cartridges!" choked Grantham. shielding his wife from the glare, while Gabriel protected Catherine. "His--his cartridge belt!" gasped Craig. "Yes! And now, out--out of here!" "Brevard? We must save his body!" cried Gabriel, pointing.