This book examines a corpus of frenetic novels – by Balzac, Barbey d’Aurevilly, Zola, Huysmans, Bloy and Bernanos – that foreground the motif of fever within a recurring masterplot: a pious young woman, just discovering her sexuality, finds herself torn between two father-figures, a doctor (typically a blood relative, often the biological father) and a priest (the spiritual father). She contracts a disease of uncertain origin, made manifest by a series of fevers that require interpretation in the light of contemporary religious, medical and literary discourses. Manzini traces the motifs of fever and frenzy back to Rousseau, the Gothic novel and Frenetic Romanticism, as well as forward to their recuperation within Surrealism, in order to produce an original history of Frenetic Catholicism in the age of realism.