I'm a little ambivalent about prequel novellas and 0.5 stories, but in this case it was a nice addition to the story. I thought Kendare Blake did a great job showing us the past, and giving us clues, without giving away the farm. And the story cemented my already formed opinions of the three protagonists- I still like Mirabella (maybe the most) but Arsinoe is awesome too, and I feel sorry for Katharine. I liked her in the first book, and she had a rough start being housed with the Arrons. Speaking of whom, the supporting players are here too- we get glimpses at Natalia and Genevieve at a much younger age, as well as Sara Westwood and High Priestess Luca. The scene with Mirabella and Luca meeting for the first time was particularly well executed, I thought.
We get a few hints as to the island being separated from the mainland as well as the fact that the queens' gifts seem to be declining in general (although Mirabella seems to buck that trend). And Jules and Joseph are part of the story as well. In fact those who think Jules will play an important role going forward will probably enjoy this very much. We see the appearance of Madrigal, and Jules gets her cat! So all in all if you're a fan of the series I would recommend this one- it's good stuff.