City of Darkness (Underworld Gods, Book 3) By Karina Halle

In "City of Darkness," the third book in the Underworld Gods series, mortal Hanna finds herself navigating her new role as the Goddess of Death in the spooky underworld of Tuonela. After agreeing to marry Tuoni, the God of Death, in exchange for her father's life, Hanna discovers that her heart is in danger as she falls for the morally grey anti-hero.

However, it's not just her heart that's at risk. Hanna and Death must work together to protect the underworld from powerful enemies, including Death's half-demon ex-wife, Louhi. With an uprising of Old Gods and skeleton armies at her fingertips, Hanna must ensure that the underworld isn't lost forever, even if it means losing each other and all they hold dear.

"City of Darkness" is a high heat dark fantasy adult romance series, perfect for fans of the Underworld Gods series and readers who enjoy morally grey characters, complex relationships, and high-stakes adventures.