Polly O'Keefe has recently come to live in the country with her grandparents, the famous scientists Alex and Kate Murry, when she wanders into a time 3,000 years before her own. Perhaps it's not an accident - as she is told by two druids: When a gate betweencircles of time opens, it opens for a reason. When the gate closes behind Polly and her gravely ill friend Zachary, the reason becomes clear. In this desperate time, can Polly keep herself and Zachary alive until the gate reopens to bring them home?