Nightwalker by Rose Harvey

Nightwalkers have no soul.
They prey on the innocent.
Above all, they are not to be trusted.

Tash dreamed of becoming a Robin—one of the brave few in the legendary Order of Song who traverse worlds, preserve magical balance, and fight for justice. When she's finally given a mission to investigate a wave of murders and a strange blight consuming her birth-world, she leaps at the chance to prove herself.

But shadows gather.

A cunning Nightwalker Dæmon from the forbidden Shadow Realm is stalking her every step. As Tash delves deeper into a mystery that threatens more than just her world, she finds herself torn between light and shadow, duty and desire.
To save the worlds she loves, Tash must face the truth about herself—and decide whether she’s strong enough to resist the darkness… or destined to become it.

For fans of rich world-hopping fantasy, fierce heroines, and the fine line between good and evil.