Demons Strike Back by Jacey Ward

Kalen – the dark demon underlord who won’t stop at anything to get what – or who – he wants.
Circe – the beautiful, innocent Valkyrie masquerading as a human supermodel.
Kalen is out for blood. The blood of a powerful demon who’s betrayed him. But he needs a Valkyrie’s powers to help him find this soon-to-be-dead demon. He’ll do whatever it takes to make that happen – even if it means manipulating and lying to the Valkyrie he fell instantly in lust with during her runway debut.
Circe knows she should stay away from the dark demon… but knowing and actually doing are two completely different things. After all, he’s so damn sweet, and protective of her. How could he possibly hurt her?
Kalen’s betting he’ll have time to break the news of who he really is – and how he’s using her, before she finds out about him some other way.
But he’s wrong.
Now, heartbroken and furious, Circe vows never to let him in again – to her heart, or her bed.