Harry Dresden, Chicago's preeminent wizard is coping with his new roommate--vampire half-brother Thomas. Harry soon has problems bigger than Thomas' clutter to deal with. Marva, one of Harry's vampire foes, summons him with a threat to his police-lieutenant friend, Karrin Murphy. Marva demands Harry get the Word of Kemmler for her, or she'll frame Murphy for murder. Harry doesn't even know what the Word is, but while he's trying to find out, and also what damage Marva will be able to do with it, several necromancers descend on Chicago. When Harry learns that the newcomers are students of Kemmler, an evil wizard who mastered ancient spirits in a way no one has since, he discovers that they are seeking the Word, too, in hopes of seizing the powerful knowledge within it and calling forth a powerful creature known as the Erlking.