Foulet shrugged, "Coincidence--possibly," he said, "but it is our only clue." "Of course," I murmured thoughtfully, "you have never been able to follow--" Foulet smiled, "Can you imagine where that airplane would be by the time we climbed down off our roofs and got to a flying field and started in pursuit?" * * * * * We descended for dinner. Foulet's story had restored my self-confidence somewhat--but I was still sore. Of course Foulet connecting my vanishing man with that disappearing airplane was absurd--but where had the man gone? Was my supposition that he had jumped to a lower roof, climbed a wall and run through the maze of alleyways in half a minute in any way less absurd? We were halfway through dinner when Brice appeared. Brice was one of the best men in Scotland Yard and I had known him many years. So, evidently, had Foulet, for his eyes flickered faintly with pleased surprise at the sight of him. Brice came directly to our table. He was bursting with victorious joy. I could feel it somehow, although his face, carefully schooled to betray no emotion, was placid and casual. All through the remainder of the meal I could feel the vibrations of his excitement. But it was only at the very end that he confided anything--and his confidence only served to make the excitement and sense of impending thrill greater. Just as he was rising to leave he shoved a tiny strip of paper across the table to me with a sidelong glance at Foulet. "Another roof-top," I read scrawled in pencil. "If you like, meet me at the flying field before dawn." If I liked! I shoved the paper across to Foulet who read it and carelessly twisted it into a spill to light his cigar. But his hand shook ever so slightly. Needless to say we went to the flying field shortly after midnight. Bruce was there, pacing up and down restlessly. Near him was a huge tri-motored biplane, its motor humming in readiness. "I've put a man on the trail in my place," Brice told us briefly. "Somebody else is going to lose the scent on a roof-top--and I'm going to watch." * * * * * We settled to our wait. To me it seemed absurdly hopeless. The flying field was on a slight rise. Below us spread the dark shadow that was Constantinople. There was no moon to give it form and substance--it was just a lake of deeper darkness, a spreading mass of silent roof-tops and minarets. How did Brice expect to see his quarry escape? Suppose he fled during the night? And even with daylight-- The first streaks of dawn found us still waiting, our ears strained for the hum of an airplane motor. But hardly had the golden rim of the sun appeared over the horizon when it came. It came from the east--straight out of the golden glory of the sun. Nearer and nearer it came; an airplane--alone.