The consciousness of the evil Overlord, successfully expelled from hero Otto's body, continues to connive within new hosts. H.I.V.E. headmaster Nero must activate his Zero Hour plan, mobilizing his allies to stop Overlord from accessing a powerful weapon system. This installment maintains the series' usual balance of fast-paced, high-tech intrigue and student interactions.

Overlord, the unkillable AI bent on taking over the world, can survive only by jumping from body to body. Only techno-wizard Otto's mind is sophisticated enough to be a permanent host, so Overlord moves to invade the hidden fortress of the H.I.V.E. School. To protect his young charges, Nero unleashes their greatest weapon yet: Zero Hour. While lacking the irreverent fun of earlier H.I.V.E. books, this sixth offering has a less convoluted story and is chock-full of whiz-bang gadgets and breakneck action. Hints of romance and a death do little to add to character development, but for series regulars that hardly matters.