And there's far worse trouble brewing. A strange darkness of the mind and heart is about to fall over the older wizards of the world, stealing away their power. Soon the young wizards of Earth and many other planets must defend the people of their worlds -- wizards and non-wizards alike -- against an invasion of a kind they've never imagined.

But mere defense won't combat the evil afoot. In company with their human and alien teammates, Kit, Nita, and Dairine must race to search worlds both known and unknown for the secret weapon that the Powers that Be have promised them - before the minions of the Lone Power find it first.

And then, for the first time in millennia, the wizards must go to war...