Mandinga (1976)

A widowed plantation owner, Richard and Rhonda, his mistress (his wife's cousin) take lots of pleasure in beating and having sex with their slaves. Clarence, the son of the owner comes back from his travels aboard. Rhonda decides to bed her nephew also even though he is engaged to be married to the daughter of a priest. There is also an illegitimate child born of a female slave that surprisingly does factor.