"Aye, aye, sir!"
Scarlett was bending low over the bows of the Hulk. In the middle of the waterway something long and lean was showing. There was a soft, metallic clang, and then, from the centre of the dark, floating object, a light flashed quickly, three times. Immediately I heard the click of the shutter of our own lamp and saw the occulting beam below flash and disappear in answer.
I knew, I think in some subconscious way, I must have known from the very first. The whole thing, in its magnificent and unsuspected daring, its malevolent simplicity, struck me like a blow. This was a German submarine; this was the channel by which the Master-Spy, von Vedal, and his agents had been sending information to the enemy! On my own quiet marshes, in Thirty Main Creek!
"One of their 'D' class, sir; same as our 'E.' Crew of fifteen, no quick-firing gun, and probably wireless. Handy little craft, sir!"
"They'll be coming aboard in a minute, Scarlett."
"Aye, aye, sir. If you look, sir, you'll see they are getting one of those collapsible boats up. New thing, sir, and very handy. Holds six. Ah!"
I could see quiet and purposeful activity round the conning-tower of the submarine. A group of dark figures was silhouetted in the moonlight, and presently a little boat, like a bobbing cork, lay by her side.
Three men got into it and it pushed off. It went towards the other side of Thirty Main.
"Concealed moorings, sir," Scarlett whispered. "They've been here before. It's dead water, and the ship'd drift, if ..."
I heard no more. I watched breathlessly. The boat went to the far side of the creek and remained there for nearly two minutes. If there was a cable, I did not see it, but presently the boat turned and came rapidly towards the Hulk.