"Hullo! hullo! All the machines are out with the men standing by, ready to go up at the first tip, except--let me see now--we've got a new fast 'Buckstead Bullet' here, which none of the men are very familiar with yet. There's that. Come if you like, old fellow. It's a bit irregular, but if there should happen to be a big attack on London, and the case warrants it, I see no reason why you shouldn't try the blamed thing. It's a single-seater, only just in from the makers, and a devil of a whizzer as well as a first class climber!" "Right-o! I'm coming straight away!" cried Dastral, waiting to hear no more, and banging down the receiver. The next minute he was outside on the pavement, forgetting all about Tim, the settlement of the bill, and everything else. Tim, however, who had heard part of the message, had already paid the bill and got outside, where he had hailed a taxi, determined not to be left behind, for his quick intuitive mind had told him which way the wind was blowing. He had had a hard job to secure the vehicle, for there had been a great demand for the same, but he had whispered Dastral's name to the chauffeur and had agreed to foot the bill however big it might be, although he had only three half-crowns left in his pocket after squaring the bill indoors. That did not bother him at all, however. Here was a chance of rendering some service, however small, to the nation at large, for he felt convinced that if only Dastral could have a chance he would bring down half a dozen raiders. Immediately, therefore, Dastral appeared at the doorway he shouted: "This way, Dastral, this way. Quick!" "What the deuce----" "Inside, old man; this is my show!" and before the bewildered pilot could finish his exclamation, he was inside and Tim was with him and the door closed. "Where to?" asked the cripple. Dastral gave the directions, and told the driver to do his utmost to get them there within an hour, or it would be too late. Within ten seconds they were whizzing away through the darkness in the direction of the Great North Road, and as there was very little traffic about, they reached their destination within three quarters of an hour. It was not a minute too soon. They had seen the searchlights at work on their way north, and towards the end of their journey they had several times heard the anti-aircraft guns blazing away at something up in the clouds. "Halt! Who goes there?" came the challenge as they reached the turning which left the main road, and finished at the aerodrome. The vehicle halted abruptly, for the driver had seen the flash of the barrel of a Smith & Weston revolver, which the air-mechanic on sentry-go held out to bar their progress. "Flight-Commander of the Royal Flying Corps," shouted the pilot, hoping that would allow him to pass, and to get on to the aerodrome immediately, but the sentry was obdurate. "Let me see your permit, sir," he asked. "Haven't got one."