Lust and Lasciviousness, book 5: Elizabeth's dutyEmma England2017

Elizabeth Bennett has always been foremost among the Bennett sisters. The brightest, and the most accomplished.
And yet, she feels a sense of failure. She has failed in her duty, to provide her much loved husband Darcy with an heir. Despite their many many efforts, Elizabeth has been unable to conceive, and that failure has cast a pall upon her marriage. It is her sisters, Jane and Mary, who come up with a bold stratagem to solve her dilemma. A forbidden, wicked stratagem. Elizabeth must lay with another man!