"Impossible!" shouted Grantham. "That hellish compound will burn for hours! And in three minutes this whole place will be a roaring furnace! Out of here--out--away! We must save the hangar, at all hazards!" Against their will, but absolutely unable to approach the now wildly-roaring fire on the floor that marked the spot where Brevard had fallen in the Battle with Plutocracy, the comrades quickly retreated. Raging fire now hemmed them on three sides. Their only avenue of escape was through the eastern windows, eight or ten feet above the ground. Hastily snatching up such of the plans and papers as he had not already secured--and some of these already were beginning to smoke and turn brown, in the infernal heat--Gabriel shielded Catherine's retreat. The others followed. Craig and Grantham first jumped from the windows, then caught Mrs. Grantham and Catherine as Gabriel helped them to escape. He himself was the last to leave the room, now a raging furnace. Together they all ran from the building, and none too soon; for suddenly the roof collapsed, a tremendous burst of crackling flames and sheaved sparks leaped high above the tree-tops, and the walls came crashing in. In the welter of incandescence, where now only the stone chimney stood--and this, too, was already cracking and swaying--Brevard had found his tomb, together with the two Air Trust spies. All that pleasant, necessary place was now a mass of white-hot ruin; all those books and pictures now had turned to ash. The five remaining comrades paused by the hangar, and looked mournfully back at the still-leaping volcano of destruction. "Poor Brevard! Poor old chap!" said Craig. He peered at the women. Neither one was crying--they were not that type--but both were pale. "I don't feel that way," said Gabriel. "Brevard is not to be pitied. He's to be envied! He died in the noblest war we can conceive--the war for the human race! And his last act was to take part in a battle that stamped out two vipers, Air Trust spies, who would have joyed to burn us all alive!" [Illustration: The spy's body burst into a sheaf of fire.] "Thank God, I got the Hell-hounds!" muttered Craig. "Two less of Slade's infamous army, anyhow." Though Gabriel knew it not, the first one to fall was the same who had battled with him in the trap at Rochester, the same who had trailed him when he, Gabriel, had left the Federal pen. So one score, at least, was settled. "They're gone, anyhow," said Gabriel, "and five of us still live--and I've still got the plans and all. Moreover, the monoplanes are safe. The quicker we get away from here, now, the better. Away, and to our last remaining refuge near Port Colborne, on the shores of Lake Erie. Other Air Trust forces may be here, before morning. We must get away!" A frightful shock awaited them when, entering the hangar--eager now to escape at once from the scene of the tragedy--they beheld their aeroplanes.