"Grace and Fury is the first in a duology. The sequel releases Summer 2019!" -- source: http://tracybanghart.com/books 8/1/2018

In an alternate world where women have no rights, two sisters face very different fates after an attempt to win the favor of the heir to the throne--one in the palace, the other on a volcanic prison island.

Sisters Serina and Nomi Tessaro were born into a world where women have no rights. Serina has been groomed her whole life to become a Grace-- to stand by the heir to the throne as a shining, subjugated example of the perfect woman. When her younger sister, Nomi, catches the heir's eye, it's Serina who takes the fall for the dangerous secret that Nomi has been hiding. There is only one way to save Serina: Nomi must take her role as a Grace until she can use her position to release her sister. But a traitor walks the halls of the palace, and one wrong move could cost Nomi everything. -- adapted from jacket