France, 1861. When an epidemic threatens to wipe out the silk trade in France, Herve Joncour (a young, married silkworm breeder) has to travel overland to distant Japan, forbidden to foreigners, to smuggle out healthy silkworms.In the course of his secret negotiations with the local baron, Joncour's attention is arrested by the man's occidental concubine. Although they are unable to exchange so much as a word, love blossoms between them, a love that is conveyed in a number of recondite messages. How their secret affair develops is told in this remarkable love story.