Brother Marie-Victorin was 46 when he met 23-year-old Marcelle Gauvreau. Both have been close to death and share the same love of God and Nature. He becomes her teacher, later she becomes his assistant. Their friendship evolves. Marie-Victorin offers Marcelle different readings on sexuality that she hastens to comment on from her own intimate experiences. In an epistolary exchange that will last until the death of Marie-Victorin, they explore human desires and "biology without a veil". This great chaste love, the love of Quebec's flora, pushes them to question their own relationship with love and Nature.