Gentlemen, I address you privately

From Kirkus Reviews:

Written with a subtle charm, filled with vivid descriptions of Brittany and its people, the book leads one, unaware, into a tragic story of a talented young musician, turned from the monastic life he had chosen, because of his secular music, and of how he became unwittingly and innocently involved in a homosexual passion for a cruel pervert, a sailor who has deserted his ship, made off with possessions of his superior officers, broken his sister's heart, and willing to trample on whatever comes his way. Fleeing the authorities together, they take refuge with a strange couple, and make companions of three girls from a brothel, girls who are themselves homosexual, and who eventually take the vagabond sailor with them to Italy, leaving tragedy behind.