The reader bounces back and forth between the two in each chapter, which can sometimes be disorienting- like reading two books at the same time (especially when the chapter has a cliffhanger). We follow Rielle as she endures magical trials meant to test her restraint and abilities- and to find out whether she was the foretold Sun Queen who could save the world (the prophecy: "The angels will return and bring ruin to the world. You will know this time by the rise of two human Queens- one of blood, and one of light. One with the power to save the world. One with the power to destroy it. Two Queens will ride. They will carry the power of the Seven. They will carry your fate in their hands."). We follow Eliana as she journeys to save her mother who was taken by unknown forces and her brother, who she wishes to get out of the Empire's reach.
In this world, angels are often powerful but cruel beings who are at war with humans (although some are good). People have the powers of the elements that they can conjure (one power per person typically, e.g. power over water), and the abilities vary with the amount of power they have. Rielle has a power over all the elements (the seven possible abilities) and she has so much that she is barely able to control it. In Eliana's time, these powers are a thing of the past and seen as myths of the past.
Overall, it was a really fascinating book, and I definitely want to continue with the series- as soon as possible! I do wish we had spent more time with one of the two women, as I felt that it was a little difficult to get truly entrenched in their lives/loves. However, I still really enjoyed it overall!