"Turn out guard!" shouted the sentry, and turning to the newcomers, he added: "Advance, Flight-Commander, and report to the guard-room." The guard-room was but a few yards further on, and the corporal of the guard, approaching the carriage, saluted, and led Dastral and Tim away to the Flight-Sergeant at the Orderly Room. He was expected, and a minute afterwards he was shaking hands with Garner, who had been waiting for him. And now there was not a moment to spare, for the presence of the raiders had been reported from the O.C. Searchlights, as hiding somewhere in the clouds between Hatfield and Barnet, trying to break through to London. Only a ring of curtain fire from the A.A. Batteries, and a cordon of long flashing lights which swept the sky from the horizon was keeping them back. Several machines had already gone up in search of the enemy and the other pilots were standing by their machines ready to "take off" immediately the order was given. Immediately, therefore, Dastral had settled with the driver of the taxi, and introduced Tim to his friend, Squadron-Commander Garner, they were led through the darkness to the shed where the "Buckstead Bullet," as she was nicknamed, lay all ready to be wheeled out. "Good! Excellent!" exclaimed Dastral, immediately he saw the little single-seater monoplane, for he had flown a similar machine several times in France. With the aid of a dark lanthorn he carefully went over her, and lovingly fingered every part of her, from the bullet-nosed fuselage which gave her her nickname, to her neat, trim little tail and rudder. The noise of the A.A. guns became louder and louder outside, as though they had discovered one of the raiders. And Dastral was just itching to go up! "Let me go up in her, Garner!" he said. "She's a beauty!" The O.C. scratched his head. He had wanted to fly her himself, for she was the only spare machine left over, and, moreover, as Dastral was not attached to the squadron, it was somewhat irregular for him to use the machine, without the express permission of the Wing Headquarters. He hesitated for a moment therefore, but, just at that instant, one of the raiders suddenly emerged from the edge of a cloud where it had been in hiding, and a fresh burst of anti-aircraft gunfire caused some excitement. "There she is!" cried some one, as one of the searchlights caught her. "As you like, Dastral. There's your target. Get into your togs quickly and I'll take the risk of it. I must leave you for a moment now. Those fellows in 'C' Flight are waiting to go up," and with that the O.C. turned round and dashed off, while Dastral, without waiting for anything further, got into a huge leathern coat, pilot's boots, and donned the flying helmet with long ear flaps and queer-looking goggles, which an air-mechanic had brought him.