Ghost in the Flames — Jonathan Moeller

Caina is now a Ghost nightfighter, with the cunning of an elite spy and the skill of a master assassin. But this time, it might take more than that to keep her alive. Caina has been sent to hunt a murderous pyromancer, a master of fiery sorcery, and she soon discovers that more is at stake than just a few murders. Because if she doesn't find the pyromancer soon, the entire world might burn. Starting with her...