Queen Vivienne, trapped in a brutal marriage, is visited by fugitive Lydia, who is hunted and desperate to stay free. Their secret alliance turns into forbidden desire and a deadly plan: to survive the palace, Lydia must become the King's mistress, so Vivienne must help kill him. By day they pretend to be enemies; by night they are lovers plotting a royal murder. When one tyrant falls, another takes his place, and the two must burn down the kingdom that tried to own them - or die trying.