He was returning to consult his companions when he suddenly heard behind him a sound like the ringing of a muffled electric bell inside the house. Hurrying on, he crouched with the other two at the foot of the wall and waited. In a few moments they heard a bolt drawn. They could see nothing, but apparently the door was being opened. Then from the doorway came a low whisper: "Geben Sie Acht," followed, as by an instantaneous after-thought, by the French words, "Prenez garde." There was no reply, but a slight rustle approached, and the three watchers, peering over the bushes, saw a woman passing in almost absolute silence down the path to the back wall. Had she left the door open? Kenneth was thinking of stealing up to it to find out when it occurred to him that the woman had perhaps gone to let in a visitor. It would be well to wait a little. Very soon he was justified. The figure of the woman, scarcely distinguishable in the gloom, reappeared. At her heels was a man. They passed along the path within twenty feet of the lurking watchers; neither spoke a word. Presently came the sound of a bolt gently shot, then all was silent again. It was pretty clear that the bell had been rung from an electric push in the garden door. Kenneth had seen none; it was probably concealed. "Shall I find it, and get the door opened?" he whispered to his companions. "That would give the whole show away," said Harry. "We don’t want to raise an alarm." "Then I don’t see that we can do anything. The only thing is to tell the captain to-morrow, and he’ll arrest the lot." "Why not?" said Ginger. "If they’re innocent, they won’t mind--not much." "But we shan’t catch them at it. You may be sure there’s nothing suspicious to be found in the daytime. We’ve got very artful men to deal with." They were still discussing their course of action when they heard the bolt drawn again. Next moment there was a perpendicular streak of dim light, which widened rapidly. The door was open; the room or lobby behind was now lit by a small oil lamp, turned very low. Through the illuminated rectangle of the doorway came a man and a woman. The man was in a British uniform. They stepped down to the path. "Stoneway!" whispered Ginger. Pressing themselves almost flat on the ground they watched the two figures walking down the path, the end of which, towards the garden wall, was scarcely reached by the feeble rays from the doorway. "Now!" murmured Kenneth. Bending double, they hastened across the grass, and slipped in through the doorway. They were in a lobby. At the further end of it was a closed door. There were doors on both sides, one of them slightly open. In the corner on the right was the staircase leading to the upper floor, and on the square-topped newel-post stood the small oil lamp.