A young American man named Justin is on holiday in Rome where he attends a mass at the Vatican. He picks up a crippled woman who has fallen in the aisle near his pew, and she seems to undergo a miraculous cure. Is it a sign from above? With the help of a powerful cardinal, Justin is elected pope. Renamed Pope Leo XIV, he sets out to liberalize the church — a dangerous course of action considering that cardinals, bishops, tradition and even murderers are arrayed against him and his helpmate, an attractive nun.