When a bridge collapses in 18th-century Peru, a Franciscan monk attempts to determine if the deaths of five travelers were an act of divine providence or mere coincidence. Brother Juniper, the protagonist, seeks to apply scientific rigor to the mystery of human suffering, hoping to map the intentions of God onto the lives of the deceased. His investigation forces him to reconstruct the histories of the victims, revealing the complex, often tragic nature of their personal connections. The narrative framework operates as a series of interconnected character studies, shifting between the past lives of the travelers and the monk's own philosophical inquiry.

Discussion often centers on the economy of the prose and the structural precision Wilder employs to connect disparate lives. Readers frequently highlight the philosophical depth of the work, noting how it avoids easy answers regarding the existence of a grand design. Critics often point to the balance between the tragic inciting incident and the intimate, character-driven explorations that follow. The book is widely recognized for its ability to condense complex existential questions into a brief, impactful narrative. Many readers appreciate the way the text invites reflection on the nature of love and the randomness of mortality.