Reign: The Cambion Series, Volume I

A half-human descendent of the demon Lilith, Captain Reign Lilim has one duty - protecting her kingdom's monarch from the demons devastating their land. For the safety of their princess, Reign's troop has spent three years isolated from society, but as hell's crumbling gates begin allowing the damned further access to their world, they're recalled to base. When Reign's mother, the Queen's second, begins unloading a lifetime's worth of secrets, Reign's left clambering for a way to save humanity from extinction.