Shadow Heir (Dark Swan 4)

New York Times bestselling author Richelle Mead returns to the Otherworld, a mystic land inextricably linked to our own - and balanced precariously on one woman's desperate courage... Shaman-for-hire Eugenie Markham strives to keep the mortal realm safe from trespassing entities. But as the Thorn Land's prophecy-haunted queen, there's no refuge for her and her soon-to-be-born children when a mysterious blight begins to devastate the Otherworld...
The spell-driven source of the blight isn't the only challenge to Eugenie's instincts. Fairy king Dorian is sacrificing everything to help, but Eugenie can't trust the synergy drawing them back together. The uneasy truce between her and her shape shifter ex-lover Kiyo is endangered by secrets he can't - or won't - reveal. And as a formidable force rises to also threaten the human world, Eugenie must use her own cursed fate as a weapon - and risk the ultimate sacrifice...