In book 1, we determine there is a kingdom killing off every once-powered (as in superpower) person from a neighboring kingdom to make sure they aren’t at risk of being overthrown, should those abilities come back. A young woman from that targeted kingdom infiltrates the royal family of the other, posing as the prince's arranged bride. She intends to kill her groom, his parents, and all other remaining members of the royal family in revenge for the relentless slaughtering of her people--including that of her parents, and the kidnapping of her sister by the king. Then she falls in love with the prince and starts to see that maybe there are other options.

In book 2 we learn more about how this happened, and the ramifications of releasing Em's (very angry) sister from her dungeon.

In book 3 we see alliances form and reform, the true colors of people who are changing, and characters becoming who they want to be rather than tools in a war they didn't start.

I tore through this trilogy. It had a solid romance in it, interesting secondary characters, surprises, and a good amount of diversity (in this world, they don't label sexuality or raise an eyebrow at who you decide to date...also, gender isn't always such a social construct. For example, yes the bride is sent from another land in a dress to marry a man for political reasons, but jobs, clothes, respect aren't so gender-based). I don't like when "war stuff" gets too complex or weighs down the character arcs in the story, and this had just the right amount. The people behind the decisions during power struggles and battles were changing, and it was reflected in those battles.

A fun series I recommend, each book just as good as its partners.