This is a simple and sweet YA fantasy adventure story. Katsya has the 'Grace' (supernatural ability) of killing. She is an unbeatable and unwilling weapon who is being used by her uncle the King to keep his subjects controlled. She is aloof and friendless apart from her cousin and secretly assists a rebel group called the Council in aiding citizens who are being oppressed.
Enter Po, a Prince from another Kingdom, searching for his grandfather who Katsa has rescued and is hiding at her castle. She and Po (who is also 'Graced' with fighting skills) are drawn to each other and form a friendship of sorts although it is obvious to the reader that they are both falling in love. Once Katsa breaks free of her Uncle's tyranny, she escapes with Po to help him search for the man who tried to kill his grandfather.
From the beginning I felt this book was aimed at young teens. The world-building, characterisation and dialogue was a little too simplistic and the behaviour of the heroine suited someone younger than Katsa actually was. I was a little surprised to see the sex scene which is definitely not graphic but it is quite openly presented to the reader and at odds with the seemingly middle school target group. It's not that I am remotely prudish but just that there is a surprising juxtaposition of open sexuality in a young person's story.
I found Katsa's reaction to Po's hidden 'Grace' overdone, as was her adamant decision never to marry. I never felt it was explained to me enough that I could understand or commiserate with her POV. I felt a bit sorry for the endlessly patient Po and I wonder if tweens would really get Katsa's feminist stance and the HFN ending.
The pace of the novel was fast and I felt like many events and concepts were introduced but only touched on lightly before racing to the next stage of the story. But this would probably suit younger readers well. I had the same reaction as another reviewer who stated this story lacked 'audience definition'.