Got to the end, and wonder why I read this.
The premise is interesting. Based on historical events in Naples in the 1300s, two sisters are the heirs to their grandfather's throne, as their father, his son, is dead. Joanna is 16, and Maria is 13. Joanna was married young to competing heir to the throne.
When their grandfather dies, chaos ensues. The nobles don't want to be ruled by a 16 year old Joanna, her husband's family maneuvers to be the true power, and suitors pursue the young Maria, hoping to gain power through her. Even the Pope intervenes multiple times in the various power struggles.
The history side of things seem pretty well researched. I thought some of the descriptions of emotions and motivations weak.
The big problem was the surprise at the end that this was a series! (Yes, I can see that in the title on Goodreads, but it wasn't on the title where I got it.) And nothing was resolved. Even in a series, I expect each book to be able to stand on its own. This book ended on a convenient point on the historical timeline, but not with any sense of completion. In good series, the end of book often has some element resolved - a secret is revealed, a character resolves to do something differently, an enemy is conquered.
I won't continue the series, even though I like well research historical fiction.