The Wicked Will Rise by Emma Dean

The Angel of Death wants his Death Knight and he will do anything to get her.

Azrael has taken Audrey and Mika has to find a way to save her sister without endangering everyone she’s sworn to protect. Too many people she thought she trusted are keeping secrets from her while the Angel of Death keeps sending his legions to test her strength and abilities.
Too many things aren’t adding up and Mika has to figure out how to defeat the Angel of Death without starting the apocalypse she’s been desperately trying to avoid. Will she be able to save Audrey without losing everything?