Kit wrangles with his sisters, the one at home shameless borrowing all wizardly perks to help her shop, and the one coming back from college still unsure whether his powers stem from Satanic bonds or not. But he's distracted by the lure of Mars, a research project that calls to him more and more directly. When Mars tests him with a series of projections based on Earth fantasies about the Red Planet, I was very glad that my recent viewing of John Carter helped me keep up. (I had a great time and I recommend the movie if you can still find it somewhere.)
Most of all, both kids are growing up. Everyone has been teasing them about being boyfriend and girlfriend for so long, but would it be so bad? Both approach this delicate question from their own perspective, and Kit gets a bit distracted when a gorgeous Martian princess decides he's her long lost lover. Oh, and also the Earth almost gets destroyed, but that's really just par for the course for these two.
Duane's Young Wizard books (this is the ninth) are fundamentally about real kids who just happen to have their own connection to the magic of the universe. The magic parts seem fuzzy; the books always manage to have the spell to do what needs to be done, but the kid parts are solid, so that the problems they face in the real world help keep their wizardly dilemmas important as well.
Religion in May: Neither kid draws on religious beliefs for strength, although magic involves a good One and the evil Deceiver. Kit's family attends church as a matter of course. So it's not about religion, but it's there positively in the background.