The story centers on Joseph Davis, a popular writer of romanticized histories, who comes to believe that some people differ fundamentally from most of us. They are more rational, possibly more talented and intelligent. His wife has increasingly become a stranger, the imminent birth of his first child has left him in a panicked state, and his rosy-tinted histories have lately begun to strike him as so much bosh. And then he overhears a conversation at his Planetarium Club, in which several of the learned members discuss the possibility of mankinds increasing intelligence being the result of the cosmic rays that are constantly bombarding us. That is what Davis and two of his cronies, obstetrician Holdman Stedding and philosophy professor Ernest Keppel, endeavor to riddle out, in this thoroughly engaging and passionate piece of work.