Blending Celtic and Norse folklore into a land with monsters both mortal and supernatural, Beyond a Darkened Shore brings us the story of a warrior princess who has to ally with the enemy of her people, so that together they can save the world from being destroyed. Ciara, the Princess of Mide, and Lief, a Jarl's son, are both chosen ones, fated (more like driven there, but semantics) to fulfil their roles as champions from the Celts and Northmen respectively to vanquish the rising threat of Nordic giants. Supernaturally charged, the duo go from enemies to lovers, supporting each other, while also trying to fulfill their personal goals of vengeance and protection.
The setting for the story is 11th century Ireland, and it comes across as a magical and dangerous land, just like you would imagine. The world-building is the strongest point of this book. While the predominant religion is Christianity, the old gods still have a hold, and Ciara has her powers from them, which makes her a pariah as well as a protector to her people. She initially despises Lief for his pagan origins, for she assumes all Northmen to be brutal and barbaric, and allying with one is anathema to her. Fearing the harm to her family and her people if the quest set upon her is unfulfilled, she reluctantly teams up with him. As they traverse the kingdoms, she has to learn to tap into the breadth of her powers, and come into the role of a leader and ruler.
As a story, it is good but quite predictable, too; except for the ending, because that was some good stuff. The romance felt a bit superficial, with them suddenly showing feelings after one disturbing incident; throughout the rest of the book, it feels that it is constantly trying to jump ahead faster (via sexual tension) so that the ending could be achieved. And I wish they had more of a discussion regarding the shared history of their people, because it seemed like it was brushed aside because they were in love (granted, their alliance does bring truce to their people but still). As characters, I did love Ciara and Lief, though, because the enemy-to-lovers trope fit very well for their personalities and brought a bit of light in this dark storyline.
Overall, as a standalone, I would say this book is pretty good with its story, pacing, world and characters.