Though eager to explore the Zaidus system, Earth-born adolescents, Meda and Kirsty, aren't too pleased to be doing it as members of an organized tour group that can best be described as boarding school on the move. Most of the places they're forced to visit are really boring, and their chaperone-cum-tutor is a harridan of the highest order. Striking out on their own seems like a much better idea, and even with limited funds and unexpected mishaps, they manage quite well - at first. But thanks to a bratty little brother, a dimension-travelling alien girl, and a handsome alien prince, their independent tour of the Zaidus planets is turning out to be far more educational than their parents had in mind.