Steadfast — Claudia Gray

Nadia, Mateo, and Verlaine saved Captive's Sound from the dark sorceress Elizabeth . . . or so they thought. But despite their best efforts, a crack opened and a new, greater evil seeped through. With Mateo as her Steadfast, Nadia's magic is magnified but her training is still incomplete. And a darker magic has begun to call Nadia. . . .

With her Steadfast, Mateo, and her best friend, Verlaine, Nadia must fight the black magic that tempts her and stop the One Beneath before he comes to claim what is his.