19th century Brazilian romantic tragedy, a story of the Mato Grosso and the inviolate patterns of the backlands' empires. Martinbo dos Santos Pereira brings Cirino Ferreira de Campos to his home to cure his daughter, Inocencia, of the fevers. Meyer, the German naturalist, is guest at the same time and arouses the father's distrust by his remarks to and of Inocencia. Cirinc, in spite of Inocencia's betrothal to Maencao Docs, chosen by her father, falls madly in love, and Inocencia, unworldly though she is, returns his passion, vows she will never marry another, preferring death. She sends Cirino to her godfather for help and gets from him a promise to back him up. Meyer names a butterfly for Inocencia; Manecao arrives to claim his bride; Inocencia defies him. In vain, both of the lovers die for their love, while back in Germany Meyer is euogised for his famous butterfly...Latin customs, character, intensified by the backlands' life, makes this a tale of another world...of the 1860's.