Fifteen-year-old Justine Ross and her family travel to London, England for what is to be a three-week vacation. While they are there, Justine's father is to speak at a medical symposium. After they arrive, Justine notices a shadowy figure dressed in black which randomly appears wherever they are. She soon realizes no one else sees the mystery figure. To top it all off, she hears a voice tell her that time is running out! Out for what? And why her? Frustration, fear and curiosity take hold of her as she seeks to learn the answer.

The answer comes during a daytrip to Stonehenge when the identity of the shadowy figure is revealed. The Ross family suddenly find themselves transported back in time to an age of sorcerers and kings and the magic of Wiltshire for a once-in-a-lifetime vacation.