Courtney Crumrin Volume 7: Tales of a Warlock

Though the Witches and Warlocks of Hillsborough keep to themselves under Ravenna's Law, there are outliers who are a danger to others. The Anti-Sorcery Society, headed by mortal Horace Crisp, seeks to destroy these individuals, and Aloysius Crumrin, an eager young man, offers his assistance - keeping his magical ancestry to himself, of course.