On her twelfth birthday, Sierva Maria, the only child of a decaying noble family in an eighteenth-century South American seaport, is bitten by a rabid dog. Believed to be possessed, she is brought to a convent for observation. And into her cell stumbles Father Cayetano Delaura. As he tends to her with holy water and sacramental oils, Delaura feels something shocking begin to occur. He has fallen in love, and it isn't long until Sierva Maria joins him in his fevered misery.