The Spy in Black by J. Storer Clouston

That evening when we had the house to ourselves, I joined Tiel in the parlour, and we had a long talk on naval matters, British and German. He knew less of British naval affairs than I did, but quite enough about German to make him a keen listener and a very suggestive talker. In fact I found him excellent company. I even suspected him at last of being a man of good birth, and quite fitting company for a German officer. But of course he may have acquired his air of breeding from mixing with men like myself. As for his name, that of course gave no guide, for I scarcely supposed that he had been Tiel throughout his adventurous career. I threw out one or two "feelers" on the subject, but no oyster could be more secretive than Adolph Tiel when he chose.

That night I heard the wind wandering noisily round the old house, and I wakened in the morning to find the rain beating on the window. Tiel came in rather late with my breakfast, and I said to him at once --