Inara spends most of her time trapped in the Roar, what she calls the hum in her head that prevents her from functioning. Zuhra is able to occasionally reach her after she uses a little bit of magic to heal her dying plants. Their mother has been so destroyed by their father's abandonment that she is unreliable caregiver. She also refuses to let them talk about or learn anything about the paladin.
Their lives will change when a boy somehow gets through the hedge - Halvor knows about the Paladin and he may be able to help understand Inara, if their mother will allow him to tell them anything. As Zuhra tries to learn how to help her sister, they set off a cascade of events that lead to more discoveries than she could have ever hoped.
The beginning of the book is slow, reinforcing the background that we know from Zuhra. Life in the citadel is isolated and boring. When the story really starts going, I was captivated by the Paladin, what little we learn of them and their cultures, as well as the dangers beyond our world. I was pretty hesitant to continue after the first slow part, but once I got about halfway through, I was really glad I had hung in there. This ended up being a really engaging fantasy for the latter half of the book.
I loved that the focus was on the sisters. Although their is some minor romance, the main love in the book is that between the two sisters. It has Frozen vibes in that way, and I was totally here for it. I also really enjoyed the world-building once we start to learn about more, and I can't wait to learn more about these worlds and culture in future books.
Overall, I think it was an okay start to the series - I would rate the first half three stars and the latter half five stars, so I am averaging the two for the overall book. With an intriguing new world and magic, SISTERS OF SHADOW AND LIGHT is a fascinating read that focuses on the bond of sisterhood.