Examining the long window minutely, they saw that it had been closed hurriedly and, hence, scarcely latched. The room, too, was in darkness. Suddenly, just as Kennedy was about to make an attempt to enter, the electric light was switched on within the room, and the pair had only time to slip round the corner of the house, when the French window opened, and four men stepped forth upon the lawn, conversing in whispers as they walked on tiptoe together across the gravel on to the grass. "I wonder what's up!" whispered Kennedy to Ella. "Let us follow and see." This they did, keeping always in the dark shadows, and retracing their footsteps to the edge of the wood close to where the railway ran. As they watched they saw that, having crossed the lawn, the four men entered a meadow adjoining, and they then recognised the figures of Drost and Ortmann with two strangers. They all walked straight to the corner where stood an old cow-shed, and into this they all four disappeared. For a full half-hour they remained there, Kennedy and his well-beloved crouching beneath a bush in wonder at what there could be in the cow-shed to detain them so long. The shed was at the base of a high wooded hill. Away, at some distance on the left, the railway-line entered the great tunnel which pierced the hill, and through it ran one of the most important railways from the Midlands to the East Coast. The reason of their long absence in that tumbledown cow-shed was certainly mysterious. The lovers strained their ears to listen, but no sound reached them. "Very curious!" whispered Kennedy. "What, I wonder, should detain them so long? There is some further mystery here, without a doubt. Something of interest is in progress." Suddenly, all four men emerged from the shed laughing and chatting in subdued tones. Drost was carrying his hat in his hand. They passed within ten yards of the lovers, and as they went by they overheard Drost say in German: "To-morrow night at 11:30 a heavy munition train will come through the tunnel. Then we shall see!" And at his words his three companions laughed merrily as they walked back to the house. Kennedy and the popular revue artiste--the girl whose name was as a household word, and whose songs were sung everywhere--crouched in silence watching the men until they had disappeared through that long French window opening on to the lawn. Then, when they were alone, Kennedy said in a low voice: "There's more going on here, Ella, than we at first anticipated--much more! I wonder what secret that old shed contains--eh?" "Let's investigate!" the girl beside him suggested eagerly. Five minutes later they emerged from the shadow, and hurrying quickly across the grass, entered the old tumbledown shed, whereupon Kennedy switched on his electric torch, when there became revealed a wide hole in the ground, which sloped away steeply in the darkness.