Taking place over five chapters, The Bridge of San Luis Rey is structured as a frame story. The first and last chapters lay out the facts of the bridge collapse, explain Brother Juniper's investigative quest, and discuss the results of the project and the priest's ultimate demise. By contrast, the three middle chapters tell the stories of the victims using a combination of Brother Juniper's findings and the additional, more intimate information about each character's interior life that only the narrator possesses.
This frame story allows Wilder to simultaneously tell the story of the bridge collapse from the perspectives of his protagonists and comment directly on the novel's thematic concerns. By explaining Brother Juniper's project at the outset of the novel, Wilder immediately communicates that the novel will explore whether or not catastrophes like the bridge collapse can or should be understood through reason and logic. The novel's three middle chapters, which represent the fruits of Brother Juniper's investigation, demonstrate that his quest is completely wrongheaded: each character's life story is far too complex for the priest, or the reader, to make a cut-and-dry decision about whether they deserve to die.
In the final section of the novel, Wilder ends the frame story by depicting the victims' loved ones—namely Doña Clara, the Abbess, and the Perichole—as they grieve and recover in the wake of the collapse. Showing how these women become more selfless and altruistic as a result of great loss, Wilder suggests that catastrophes like the bridge collapse are best understood not through reason but through the loving relationships that survive individual deaths.
