The devil on the road is British university student John Webster, who--courting chance on his motorcycle--chances upon an old barn in a rainstorm and is persuaded to stay on by its owner, whose reasons are clearly urgent but not forthcoming. Once there the young man is summoned by a cat to the 17th century, where a witch hunt is in progress and a young girl who bravely befriends the accused is about to become one of them. It is for the girl, Johanna, that Webster (a likely devil to his victims) storms the witch catcher and his followers with bike, explosives, and a sawed-off shotgun; but once he has brought Johanna safely to the 20th century he discovers that she is indeed a ""green"" or ""blessing"" witch--put otherwise, a link with life itself. . . or the ""Lady Chance"" that Webster had thought he was pursuing--and he finds himself unequal to the commitment she requires. But such a summary can't convey the textures of Westall's contemporary and historical reality, the seamless brilliance of his time shifts (once, while kneading bread, Johanna compares that activity with her maneuvering among the ""folds"" of time), or the subtlety with which he plays off the rootless and mechanized Webster against Johanna's earthy craft.