Wizards at war
(Book)

Nita and Kit rejoin forces when a strange darkness of the mind overcomes the older wizards, stealing away their power, and forcing the younger wizards to go to war to save the world. Nita and Kit come home from their "vacation" to find that all of Earth's higher-up wizards have vanished--and worse, they've disappeared at a time when very strange events are taking place in every corner of the planet. Soon enough Kit, Nita, and Nita's sister discover that their friends and fellow wizards are busy fighting a terrifying invader. The enemy is not a simple army, which would be easy enough to defeat, but a coalition of dark wizards bent on taking the planet for their master, the sinister Lone Power.