Data breaks a Borg drone's neck in a fit of rage his programming shouldn't allow, and the mystery of how pulls the Enterprise-D into a trap: a splinter faction of individual, emotional Borg led by Data's own brother Lore. Carey's novelization follows Picard's crew stranded on Lore's world, racing to pull Data back from an emotion chip that's turning him into the weapon Lore always wanted, and to stop a Borg army built to wipe out organic life.
Summary by Loreful, from public sources