The lady of the sorrows - Cecilia Dart-Thornton

Though her memory remains clouded by sorcery, Imrhien (heroine of THE ILL-MADE MUTE) must take vital news to the King-Emperor of Caermelor, hoping also to find there the fearless ranger who has won her heart. She assumes the identity of 'Rohain', a noblewoman visiting from the distant Sorrow Isles, but finds the King and his rangers heading off to battle the Unseelie hordes. Meanwhile, awaiting their return, the newcomer must survive in a court where treachery and deceit are as deadly as any eldritch peril.

Worse still, attacks by nightmare monsters of the Wild Hunt grow ever more frequent and brutal, and when evil forces lay siege to the royal sanctuary on a hidden mystic island, she realises with horror that she herself is the real target of these onslaughts -- but has no idea why.