The Songbird and the Heart of Stone by Carissa Broadbent (Crowns of Nyaxia Book Three)

Mische lost everything when she was forcibly Turned into a vampire – her home, her humanity and, most devastating of all, the love of the sun god to whom she had devoted her life. Now, sentenced to death for murdering the vampire prince who Turned her, redemption feels impossible.

When Mische is saved by Asar, the bastard prince of the House of Shadow with a brutal past, she is forced into a mission worse than execution: a journey to the underworld to resurrect the god of death himself. But Mische is offered a chance at salvation by her sun god. All she has to do is betray Asar – and kill the god of death.

In the underworld, Mische and Asar must face treacherous trials, colossal beasts and the vengeful ghosts of their pasts. But most dangerous of all is the alluring call of the darkness, and Mische’s forbidden attraction to Asar. As the moment of her betrayal looms, Mische is forced to choose between faith and love – a decision that could lead to her redemption or her ruin . . .