Dick Young, a publisher on a temporary break from work, receives an invitation for a vacation at the home of his longtime college friend, Professor Magnus, who is an unconventional scientist. Magnus invites him to participate in an experimental research project involving a potent drug that has the ability to temporarily transport users into the rich historical past of the Par, Tywardreath, and the surrounding Cornwall region. As a series of events unfolds, blending together elements of both the past and the present, the narratives of Dick, his American wife Vita, her two children, Professor Magnus, and other local inhabitants who exist in both time frames, become intricately intertwined. This culminates in a conclusion where the boundaries between the past and the present blur and merge.
