Iron Garland (Harbinger, 3, Band 3)

Wall Street Journal bestselling author Jeff Wheeler continues his majestic Harbinger series in a world where motivations are as mysterious as magic.
For three years, Sera Fitzempress has been a pawn in a gilded prison―the floating manor of Pavenham Sky. Disgraced and exiled from society, she has been isolated from the downtrodden she’s determined to liberate. But although Sera may seem subservient on the outside, the stubborn princess has only become emboldened.
Now in charge of her family’s estate, Cettie Pratt has grown into an independent young woman, although she continues to be tested by the high society of the clouds. Advancing in the magic of the Mysteries, Cettie is also a useful tool of defense during turbulent times. However, as more of Cettie’s mysterious past comes to light, her greatest challenge may be a reckless stranger with a dark secret.
The fog of war is drawing in, and with it comes a startling new enemy who may unravel secrets that both women would prefer stay hidden. But their secrets may be the only way to stop the coming darkness…