The Spy in Black

A German soldier is put ashore on and English island, from a submarine, for a three day mission to gain information about British fleet movements.  The first part of the story is told from his viewpoint, as he tries to avert detection and meet up with his contact. In the second part, the plot thickens as the master spy, his contact, executes his plot of impersonation (that of a village Vicar), and sets himself up to fulfill his part in the mission. The soldier considers himself, as just that, a soldier on a mission, not a spy, and has issues with the cold ruthlessness of his contact. Yes, there is a beautiful lady spy for whom he learns to care. Is the story about the soldier who lands in the black of night clothed in a dark jumper to hide his uniform, the master spy, who is disguised in the black clothing of a Vicar, or the black deeds of the profession itself? Who, actually, is The Spy in Black?