There are 4 books in the Underworld Gods series. The newest book is Goddess of Light which came out in 2025.

1
River of Shadows

Book cover of River of Shadows
In order to save my father, I have to marry the God of Death.

River of Shadows is a spicy, captivating, and atmospheric adult dark fantasy romance inspired by Finnish mythology, from the New York Times bestselling author of Black Sunshine. Perfect for those who want Hades/Persephone and Beauty and…

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2
Crown of Crimson

Book cover of Crown of Crimson
The next thrilling instalment in the Underworld Gods series. Perfect for readers who want high steam Hades/Persephone and Beauty and the Beast vibes with a dark Nordic folklore twist.

All Hanna Heikkinen wants is to be reunited with her father again. After all, that's why she ventured into the dark…

3
City of Darkness

Book cover of City of Darkness
From the New York Times bestselling author of River of Shadows and A Ship of Bones and Teeth comes CITY OF DARKNESS the third book in the Underworld Gods series, a high heat dark fantasy adult romance series.

When mortal Hanna agreed to marry Tuoni, the God of Death, in…

4
Goddess of Light

Book cover of Goddess of Light

The battle for the Underworld has begun...

When Hanna Heikkinen sacrificed herself to the God of Death to save her father, she never imagined she'd fall in love with the grumpy god—or thrive as Queen of Tuonela. Nor did she expect to uncover the truth of her divine lineage, a…