What were the social and spiritual consequences of the brutal anticlerical purges enacted by the Mexican government during the late 1930s? Graham Greene, an established British novelist and journalist, documents his expedition through the southern states of Mexico to observe the impact of President Calles's policies. He utilizes a reportorial framework to analyze the destruction of religious infrastructure and the displacement of the clergy, ultimately arguing that the state's aggressive secularization campaign left a profound void in the lives of the rural population.

Critics and scholars frequently identify this work as a vital precursor to Greene's later fictional output, specifically regarding his thematic exploration of faith under duress. Readers often note the stark, atmospheric quality of the prose, which captures the desolation of the region with clinical precision.