"I’ll stay, sir, but what about you? This is your third night-sitting, and you’ve had nothing since lunch. Shall I order supper for you?" "Oh, thanks, Jones, but I’d forgotten. Yes, you may order me coffee and a sandwich, and get something for yourself. You’re getting the strain as well, and I don’t want you to break down." When left alone, Colonel Tempest once more began to pace the soft-carpeted room, much as a captain paces the bridge when his thoughts are unduly disturbed by some untoward event during the watch of the second officer. Every other minute he consulted his watch, and wondered why the time passed so slowly. Twice he rang down to the lobby attendant and asked if Captain Keane had arrived, and twice the same answer was returned. Then he looked at the maps on the wall, and followed with his finger the trail of the All-Red Route which the aerial liners followed, linking up the empire and half the world. Now and again he would glance shrewdly at the large map of Germany, as a skipper eyes the weather quarter when a storm is brewing. Occasionally he would murmur half aloud:-- "A silent engine ... three hundred miles an hour. Gee whiz! but they have beaten us two to one. We shall never catch them." Then a slight sound caught his ears from outside the great building. The soft purr of an approaching Rolls-Royce motor and the sharp blast of a Klaxon horn followed. "At last!" he cried. "Here they come!" *CHAPTER IV* *A MIDNIGHT CONSULTATION* The next moment the door burst open and two men in flying helmets and leathern coats entered the room, and saluted the Colonel. Without any ceremony the latter greeted them warmly, almost joyously, for their cheerful presence gave almost instant relief to his over-burdened mind. "Good evening, Keane. Good evening, Sharpe," he exclaimed, stepping forward and gripping each of them warmly by the hand. "Good evening, sir." "Now, have you discovered anything?" began the chief, without waiting for them to divest themselves of their heavy gear. Keane looked at the Commissioner for a second or two and then answered:-- "Yes, and no, Colonel." "H’m. That means something and nothing, I presume." "Exactly, sir," continued Keane, who acted the part of spokesman. Then, speaking more solemnly, and in lowered tones, he continued, "We are up against something abnormal; I had almost said something supernatural. When you recalled us we were hot on the trail of the man who, in my opinion, is behind this conspiracy." "You mean this Professor Weissmann?" added the chief of the aerial police. Keane nodded. "I thought so. This man is evidently an evil genius of very high mental calibre, and he has determined, out of personal revenge for the defeat of Germany, to thwart the Allies, and in particular Great Britain."