The Spy in Black by Joseph Storer Clouston, Fiction, Action & Adventure, Suspense, War & Military (Paperback) (ISBN-13: 9781463800055)

If any one had been watching the bay that August night (which, fortunately for us, there was not), they would have seen up till an hour after midnight as lonely and peaceful a scene as if it had been some inlet in Greenland. The war might have been waging on another planet. The segment of a waning moon was just rising, but the sky was covered with clouds, except right overhead where a bevy of stars twinkled, and it was a dim though not a dark night. The sea was as flat and calm as you can ever get on an Atlantic coast -- a glassy surface, but always a gentle regular bursting of foam upon the beach. In a semicircle the shore rose black, towering at either horn (and especially on the south) into high dark cliffs.

It was wartime, and I was preparing to infiltrate the enemy. A serious, serious moment.