Wildfire by Ilona Andrews

From Ilona Andrews, #1 New York Times bestselling author, the thrilling conclusion to her Hidden Legacy series, as Nevada and Rogan grapple with a power beyond even their imagination...
Nevada Baylor can't decide which is more frustrating-harnessing her truthseeker abilities or dealing with Connor "Mad" Rogan and their evolving relationship. Yes, the billionaire Prime is helping her navigate the complex magical world in which she's become a crucial player-and sometimes a pawn-but she also has to deal with his ex-fiancée, whose husband has disappeared, and whose damsel-in-distress act is wearing very, very thin.
Rogan faces his own challenges, too, as Nevada's magical rank has made her a desirable match for other Primes. Controlling his immense powers is child's play next to controlling his conflicting emotions. And now he and Nevada are confronted by a new threat within her own family. Can they face this together? Or is their world about to go up in smoke?