Miss Gail's first book on the Middle Ages, Avignon in Flower, was, at least from the standpoint of history, something of a catastrophe. Since then, she has come rather a long way. This second book is the story of the Great Schism, that period of almost four decades when the Roman Church was governed, more or less, by three rival popes--a Roman, an Avignensean, and a Pisan--a phenomenon which completed the ruin of the medieval papacy and rent asunder the loyalties of Europe. The author has her facts straight, and she tells the story with a certain panache. She has a disconcerting tendency, however, to view the record of human experience as something of a comic opera provided for the delectation of posterity, and nowhere in the book does one find evidence of a recognition of the momentous nature of the events described--effects from which the West, to this day, has not fully recovered. Moreover, The Three Popes bears witness, along with Avignon, to the author's preference for secondary (and not always reliable) sources. The inescapable conclusion is that this is a highly readable and amusing account of the Schism; but it should not be mistaken for ""history"" in the strict sense of that term.