Caitrin, her cousin Chase, and their friends Osbourne and Strom are farmer's kids, living ordinary lives, until events start to close in on them. Their land is about to be invaded by a powerful and expanding empire, and a religious prophecy is about to come to fruition. Uncomfortably for her, Caitrin, it seems, is the Herald of the return of the Comet, which is the symbol or vehicle of a goddess.
With the Comet becoming visible in the sky, Caitrin now has power, and and this teenager who never expected this is quite convincingly inept and clumsy in her first (initially accidental) uses of it. This quickly gets her a reputation as a witch--the dangerous kind that no sensible person wants around.
And of course, no one believes the prophecy about the invasion until the empire's ships are on the horizon.
Caitrin and her friends' efforts to survive the initial invasion while Caitrin struggles to master her new power dominate this first volume, and we begin to get clues to an over-arching story with a longer history than the four friends suspect.
I like these characters. They're good-hearted and fallible. They have some really smart ideas, and they also screw up sometimes. They don't always do the right thing, but they do always try. Even with traumatic events for the kids, and disaster befalling their land, this is, as odd as this may sound, a very good-natured book, and I enjoyed my time with it. I could quibble endlessly on details. Societies with mediaeval-level technology are not going to have rough gender equality. It's just not going to happen because of the birthrate required to keep those societies viable. If the planet (note that there's some suggestion we may not be talking about Earth) really passes through a comet storm every thousand years or so, there are going to be some impacts that are really not good for life on that planet. Who cares? This is a fun book! Go with it!
At least, I had no difficulty doing so, and these are the kinds of things that often make me quite cranky.
Audiobook, so I almost certainly bought it rather than getting a review copy. In any case, I'm reviewing it voluntarily.