A biography of this 16th century French queen, fabled beauty, and daughter of Catherine de Medici is as useful an instrument as any to unsnarl the family feuds, alliances and religious conflicts surrounding Catherine and the ""three Henri's"": Marguerite's brother Henri III, Henri of Navarre (her husband) and Henri de Guise (her reputed lover and leader of a sizeable power sector). Chamberlin is more adept at clarifying political tangles than at portraiture -- in fact he is apt to cast out snap and unfounded judgments. On one page he declares that Marguerite's beauty ""defied the ravages of time"" and on another that Marguerite at fifty, alas, ""was simply a grotesque."" However, the author does manage to follow the zigzag directions of the often lunatic family of that formidable widow, Catherine de Midici, whom he blithly sketches off as a ""dusty, plump black duck."" It was Catherine who usually orchestrated the power ploys of her family and the powerful houses of France, carefully applying ""no more pressure than was needed to move a particular obstacle"" -- the St. Bartholomew's Day massacre, however, might have been the result of her using Italian city-state manipulative politics in a large country. The author follows Marguerite's career through marriage (unhappy), exile and alliance with brother Hercule, travels, divorce and final isolation. Like the author's Renaissance Italian studies, events take on more color and conviction than personalities, which seem a bit out of focus.