An Unkindness of Ghosts, Rivers Solomon

For generations, the Matilda has ferried the last of humanity to a mythical Promised Land. On its way, the ship's leaders have imposed harsh moral restrictions and deep indignities on dark-skinned sharecroppers like Aster, who they consider to be less than human. When the autopsy of Matilda's sovereign reveals a surprising link between his death and her mother's suicide some quarter-century before, Aster retraces her mother's footsteps. Embroiled in a grudge with a brutal overseer and sowing the seeds of civil war, Aster learns there may be a way off the ship if she's willing to fight for it.