The Adventure of the Demonic Ox — Lois McMaster Bujold

When sorcerer Learned Penric hears of the suspected demonic possession of an ox at his brother-in-law’s bridgebuilding worksite, he thinks it an excellent opportunity to tutor his adopted daughter and student sorceress Otta in one of their Temple duties: identifying and restraining such wild chaos elementals before harm comes to their hosts or surroundings.What begins as an instructive family outing turns anything but routine when a mountain search becomes a much more frightening adventure for Penric and his charges. What is undergone there by both mentor and students will yield lessons both unexpected and far-reaching.