Imprisoned, starved and left with no memories, Thalia awakens to find herself at the mercy of an evil cult known as the Septori. Their leader has chosen Thalia as the test subject for a torture device of untold power, designed to change and twist her into something that is neither human nor Denai.
Escaping, Thalia finds an unwilling warrior to protect her and an unlikely Denai to befriend her. After finding a home at the Citadel as a servant, Thalia’s worst nightmare comes to life and she begins to show signs of power. Scared and unable to control her gifts, she tries to hide her past to fit in among the Denai. But the Septori want their latest test subject back and will stop at nothing to retrieve her, dead or alive.
After finally settling into her new life at the Citadel, Thalia is reunited with her father, who is disturbed at the changes within her. Risking banishment, Thalia must work to prove to her clan and herself that she is still capable of leading them. The problem is, her memories haven’t returned, and she cannot shake the feeling that she doesn’t belong.
Thalia discovers that betrayal runs deep within her clan, just as she sets out to join Joss and Kael in doing the one thing she fears most: track the Septori to save Joss’ kidnapped sister. Along the way, she must confront her own fears on a journey of self-discovery that will take her deep into the stronghold of Denai; as they travel to the ancient floating city of Skyfell.
Every journey has an end.
Unable to find the answers she sought in Skyfell, Thalia, Joss, and Kael travel to Haven with a prisoner in tow. An attack on the road waylays their plans, and Thalia finds herself traveling alone with Kael to the hidden sanctuary of the SwordBrothers.
But war is on the horizon and the Raven is amassing his army. This time, the target is not Calandry, but the Sirens of Sinnedor. When family ties are revealed, Thalia must choose sides. Desperate to break the final seal on her power and save those she loves, will Thalia willingly taste the bitter pain of the iron butterfly machine one final time?