The Power and the Glory is set in Mexico in the pre-war period, when President Calles' atheist and secularist government was wreaking its murderous persecution of Catholicism, in which churches were closed and many priests driven out, imprisoned or killed.
The book is like layers of an orange. Initially we read a small section describing how a cynical journalist sitting in his hotel room overlooks a small and timid man being lined up before a firing squad. The next layer consists of an account of a Catholic mother reading her daughters and son a hagiographical account of a priest martyred in the persectuions. Then the deeper story begins when we read of a small and somewhat inconspicuous man seeking bread and wine, at a time when wine was forbidden by the teetotal government. We know that this is the small man whose execution is happening in the town square, and we know that he seeks these items to consecrate at mass.
There are four villains who dog the priest throughout the tale. The Mestizo is a Satanic figure bent on gaining the reward for capturing the priest. He knows who the priest is, but is too weak to arrest him, so he must bide his time and set a trap. The lieutenant is a sincere atheist bent on arresting the priest, as he disbelieves in religion. There is also the Gringo bandit, wanted by the authorities, he shows no interest in the priest, but his fate is wound up with the priest's. There is also the failed priest, Father Jose, who has taken a bribe to abandon his faith. Greene's scorn for this character comes through in the book, as he depicts a man cowardly and degraded, who has fallen from faith and wisdom, and whom no one respects.
The priest, who like most characters in the novel is never named, is a stumbling inadequate. He has remained faithful to his mission. While wanting to run away someone's spiritual need always calls him to stay. Yet he is lonely and drinks too much brandy, and one night when drunk he sired a child, leading him to regret his fall from priestly standards. Yet he never betrays his mission. It is this that leads him to his doom.
Having escaped to Guatemala he is ready to say mass when the Mestizo arrives. The ,message is that the Gringo bandit has been wounded and captured, and is pleading for a priest before he dies. Without absolution from a priest he will die unshriven. The priest suspects a trap, but faithful to his ministry he returns with the Mestizo, to find the bandit unrepentant and the lieutenant waiting. The priest is finally taken, the lieutenant gets his prey and the Mestizo his reward. There is only one fate: execution.