The book review says - Somewhere beyond time, the Kalevide, golden haired King of Viru, stands watch at the gates of Hell, on the back of a snow-white mare. But legends proclaim he will return, in the nation's darkest hour, to vanquish the forces of darkness. A tragic hero who wrestled and chained the Lord of the Underworld yet could not save those he loved from destruction.
This is a retelling of the ancient national epic of Estonia, and is related to the Finish _Kalevala_. It is filled with war and magic, demons and beautiful maidens, and archetypal images.
As a student of mythology, I found it interesting, but the story moves slowly in many places.