The Vanishing Throne by Elizabeth May

Everything she loved is gone.

Trapped. Aileana Kameron, the Falconer, disappeared through the fae portal she was trying to close forever. Now she wakes in an alien world of mirrors, magic, and deception—a prisoner of the evil fae Lonnrach, who has a desperate and deadly plan for his new captive.

Tortured. Time after agonizing time Lonnrach steals Aileana’s memories, searching for knowledge to save his world. Just when she’s about to lose all hope, Aileana is rescued by an unexpected ally and returns home, only to confront a terrifying truth. The city of Edinburgh is now an unrecognizable wasteland. And Aileana knows the devastation is all her fault.

Transformed. The few human survivors are living in an underground colony, in an uneasy truce with a remnant of the fae. It is a fragile alliance, but an even greater danger awaits: the human and fae worlds may disappear forever. Only Aileana can save both worlds, but in order to do so she must awaken her latent Falconer powers. And the price of doing so might be her life…