Charley is worried! Her archaeologist parents have been marooned on a sinking island and, when an antique mirror becomes a gateway to another world, she too faces many dangers. But she is helped by Charles, a boy version of herself she meets there, with whom she is unknowingly linked to a great source of magic. They must now flee through further magic mirrors to other worlds, pursued by horrific magical creatures sent by a sinister wizard who wants to tear this secret from them.

Charley’s magical aunt accompanies them – at least her spirit does in the body of the cat, Selena. They travel through worlds that are both similar yet unlike their own in different times. They must journey from Charles’ Victorian home, through a future world where magic and science are in harmony, and finally in an ancient Britain where they meet versions of Merlin and Arthur. Finally, on the island of Lyonesse, they face the wizard himself within a magical maze in a desperate battle to rescue her parents and return them safely to their own world and time.